I had the same error but none of these solutions applied to my situation.
If you are in the same boat, consider if the problem is one of the columns within your Insert A Row and not the entity name itself.
I was copy Billing Template records over to the Billing table

The "values" that drives the looping is outputs('List_rows_for_AIS_Billing_Template')?['body/value'] -- from a List Rows from a Dataverse entity/table
What I discovered was the problem wasn't my entity at all, but one of the columns in a very long list of fields on that entity -- Owners.
The two entities are supposed to be mirror images of each other structurally, so I just copied over field by field, including Owner.
When I couldn't figure out the error I decided to just do a simple Insert Row with only the one required field -- and it worked.
So I started adding in fields 5 at a time to find the culprit, and it was Owners, which is system-created field on this custom entity.
I also dropped Record Created On and Status Reason -- not because they were giving me any errors but because it didn't make sense to carry them forward. Let the system default the values -- and it didn't give an error for not having them populated.
I wasted 3 hours on this thinking it was my connection, a firewall problem, plural vs. singular naming, Name vs. Entity Name...... All because of a column WITHIN the entity/update statement and not the entity itself.
Hope this helps someone else.
Microsoft, you need to step up your game on error reporting.