Save me ST, you’re my only hope

I work in Powerpoint a fair amount, charting data etc. I’m currently running Office 2019.

In the last month or so Powerpoint has started a hugely frustrating issue where I drop data into a chart, hit save, go back in to edit the data in the chart and… half of what I entered in the data has gone missing. Essentially, the chart datasheet has reverted back to a random stage about halfway through my data entry, and includes nothing that was entered after that point.
Copying the page, and the chart, copies the problem. Turning off autosave/ autorecover doesn’t affect it. I thought for a while it might be something to do with Office Document Cache (despite not having it set up for cloud saves), but not having much luck there.
Reinstalling Office hasn’t solved it either.

Can anyone help?!
It’s pretty similar to this (unsolved) issue: https://answers.microsoft.com/en-us/msoffice/forum/all/powerpoint-chart-data-is-reverted-after-i/ac019b8d-8a6d-49b3-9a07-aa2a5e92bae7