Having the same issue.

I had the same error, and I was trying to append linked records to a field during my automation. One of my conditional group’s conditions was to check if the linked record field’s list length was empty. Even though this option was allowed, it always produced the “Field cannot accept the provided value: Could not find matching rows for string” error.

My solution: Don’t check if the length is empty (I should be checking if the list itself is empty)! My two options for a fix, in this case:

1. Change the conditional to check if the list length was number-based (e.g. length != 0, length <1, etc.).
2. Check if the list of linked records IDs (NOT its length property) is empty.

It helped to look at the Automation Log and focus on the conditional parameters!