The editing panel for an account is defaulting to the wrong balance type. The simplest way to explain this is with a couple of screenshots.
First, the header for the credit card transactions list:
Then, the relevant portion of the editing panel for the same account (this is the panel that pops up when you click on the 3-dot menu next to the account balance in the header):
One shows that the account is set to "Balance w/ pending" while the other shows that the account is set to "Bank balance."