Grouping transactions for auto match rule error

Summary:

When I tried to change the match type to approved, an errors stop me from changing the status

Content (required):

I have Many to 1/1 to many rules that use grouping. When I create the rules no error occurs, but when I try to change the match type status to approved, the error will pop out. If I go back and save the rules with grouping again, sometimes I can change the status from pending to approved. (Sometimes it removes the grouping for me)

I don't know why I get these errors and why saving again can fix the errors. Is this a bug or I did something wrong.