Thank you so much @BPLightlog and  @Firedog for your kind and reassuring comments and all the helpful and knowledgeable advice.

You’re right about my need to be patient!  You know, I hadn’t even considered how busy things would be the tariff change on the 1st, probably because I’m on fixed tariff until May.

When things return to normal I shall definitely be exploring the Bright app…makes a lot of sense to have the data locally available so to speak, especially, as you correctly say, my IHD has been fine throughout all this.

It’s amazing how I’ve come to rely on checking the half-hourly usage figures over the Power Move challenge particularly; I’m so looking forward to doing that again, and thank you so much for all the reassurance about the data not being actually irretrievable even though I can’t see it at the moment!

I am not alone!  I shall learn patience! “Everything comes to him who waits” and so forth!!

Thanks so much again…

OK. Over the past couple of weeks, my online OVO account has been in a state of flux following a meter exchange. There are missing readings, missing half-hour usage data, inexplicable usage estimates and a spurious statement for September. I’m confident (!) that it will all come right before too long, preferably before 31 October.

During this turbulent period, all my usage data have been consistently available from n3rgy via Guy Lipman’s brilliant utility,¹ sometimes only a few moments after that usage took place. Often, though, there’s a delay of an hour or two. I find this route the most straightforward of the various ones I’ve tried; the CSV files it produces, especially for a single day, are arranged with local timestamps ready to copy and paste into an Excel sheet. I may find time to write a step-by-step guide to using this source.
  

1 Note to @BPLightlog: this is particularly aimed at Octopus customers, e.g. with built-in tariff data, but it works for most others too. Have you had a look at it?

Only very briefly as my Glow IHD and Bright data feed automatically takes price feeds and presents my data just right. I also use the Glowmarkt data download 

Hello @Firedog I had a quick look at n3rgy, but unfortunately it couldn’t find my MPAN…I’m guessing g because my Communications Hub is still not connected to Wan.

Looks useful though, like the glowmrkt data download (whenever I may succeed in downloading electricity data in the future!)

Thanks….

I did a quick check some weeks ago, and I found only one day where OVO was missing my Hh figures - 21 March 2023. Those figures are clearly still available from DCC, so there must be a cut-off point when OVO stops bothering about back-filling missing historical data. Because they can still be retrieved by other routes, it’s of no consequence to me or, I suspect, anybody else.

ToU billing depends on meter readings on the different ToU registers, not on the Hh usage figures.
  

I’ve been doing a little bit of checking with just a couple of days’ figures from my new meter. If I add up the Hh data for the peak and offpeak periods separately and add them together, I find that the difference in the totals is within 1Wh. The difference between registers, though, is up to 15Wh. This presumably reflects the millisecond timing differences between recording register states on the one hand and the Hh data for the periods preceding and following the ToU change on the other:

 

I’ll be keeping an eye on this when my meter readings start appearing again, but on this limited basis I’m pleasantly surprised at the apparent accuracy. 

Not sure about that .. my tariff now has different half hourly pricing but my meter only has 2 registers as far as I know. 
 

Having looked in detail at my pre-move data, I can see lots of days with missing data. I can see it’s there via Hugo/Bright etc but missing in the OVO feed

It does seem a rather hit and miss - will try again later in the month; I’ve got two Ovo accounts, glowmarkt is the only fully working 30min 3-digit download for both, here’s my experience, yours clearly vary! Downloads from all of the non-Ovo sources below can be pasted straight into my Power Move spreadsheet (Guylipman format needs columns A&E, all others A&B).

Home account:

• smarttariffsmartcomparison.org: no data after 2nd Oct - emailed, got a swift reply saying prototype service, try my account, now activated on glowmarkt.
• glowmarkt.com: All 30min data available - so far working a treat!
• n3rgy.com: 30min 3 digit available BUT has a 2-day missing block (02/03 Oct) - emailed support Fri PM.
• guylipman.com: (not surprisingly) same gaps as n3rgy.com @Firedog 
• Ovo Website and app: All recent 30min data visible (to 2 digits), app's 30min download only possible day-by-day and then not datestamped (so not suitable for easy Excel processing). That itself is the subject of this forum.

Shared Driveway account:

• smarttariffsmartcomparison.org: Same issue as above, so asked for glowmarkt activation, again got a very quick positive reply.
• glowmarkt.com: All 30min data available - so far working a treat!
• n3rgy.com: Keeps saying "Unsuccessful Consent" retry later.
• Ovo Website and app: Same as above

Somebody has marked this solved by a post that is clearly not solving it. Can this be undone?

I would say that my original query was solved a long time ago in this thread but by far the most useful contribution has come from @Alandamore who deserves great credit for both his spreadsheet and his work on data access. 

More about monitoring…

Building on the excellent work done by @Alandamore (and stealing his spreadsheet), I have produced a visual monitoring tool which you are welcome to access by clicking here.

Instructions:

1. Set parameters (currently set for Autumn PM Challenge)
2. Download data from Glowmarkt and paste into the appropriate sheet
3. Adjust the size of the Calculations table to accommodate all the data up to the end of the last full day’s data (you can leave a part day but it will give a zero reading for that day at the end of the graph)
4. Right click anywhere on the pivot table and click Refresh
5. View monitoring chart.

I hope you find this useful.