What's causing Error 160203 when trying to delete rows from ArcOnline layer in Model Builder

[LindsayRaabe_FPCWA]

I'm using Model Builder to modify data that exists locally on our server plus also in ArcOnline. I'm at the pointy end now and nearly finished, but have hit the below snag when trying to delete rows from a hosted feature layer. 

I've definitely got Edit permission and I've looked up the ERROR 160203 link (which was pretty much useless). Can anyone think of a cause/solution for this? I'm really wanting to utilise the improved Append function of V2.8 to update our AGO datasets which we currently update manually due to the old append timing being extremely slow (and sometimes timing out). 

Some additional context: It looks like it might be related to the volume of data being deleted (approx. 23,000 rows) it appears to work ok on ArcOnline hosted feature layers with 588 rows in them without issue (still a bit slow at 3 min 22 secs compared to 9.61 seconds to Append the same amount of data). Whatever was done to the Append tool to make that work better needs to be applied here too!

[LindsayRaabe_FPCWA · Accepted solution]

Turns out it was layer issues. No matter how many records I tried to delete, or how I tried to delete them, it wouldn't let me. Have deleted the layer in ArcOnline and published a complete new one and now the tool works (although yet to try on 20,000+ records).