When I use the "update sharepoint list item"-action which references one of my sharepoint lists, the fields of the Sharepoint-item get erased if I leave these fields blank on the action-card:
When I look at "View code" of this action card I can see that the flow sends an empty value, probably the reason why these fields get erased on the item:
But this behaviour doesn't happen on every sharepoint list !
I created a new list, added an "update sharepoint list item"-action to the flow which references this new list, and this flow doesn't erase the fields of the sharepoint item. This behaviour is confirmed by the "View code"-window:
Do you have any special settings on this list?
The issue you mentioned didn’t occur on my side.
Could you please take another try with it?
If the issue still exists, please share a URL of the problem flow, I will help confirm it.