Posting here for maximum traffic.
I’ve just spent ages on the Bulb website trying to give them meter readings. There was a 15 minute queue to get into the site, and then when I tried to submit I got an error message telling me I couldn’t give them the reading and to try again in 24 hours. I ignored that and resubmitted multiple times but just getting the same error message.
Anyway, after giving up, I happened to look in my email and saw that I had about 100 emails from them thanking me for my readings.
So if you get the error message don’t waste time trying to resubmit, check your email and maybe the readings will have already been registered.
Hope this saves someone some time. The queue time for the website was pretty accurate btw.