I have one client for which Quickbooks Online is not automatically matching checks that cleared the bank to checks in Quickbooks. I have to manually match each check, which is a time suck. I've contacted Quickbooks support in the past and the person I talked to couldn't figure out the problem and said there wasn't anything they could do. I'm going to contact support again today to see if I can get someone who can actually help, but thought I'd try the community too in case they can't help.
QuickBooks will consider it as a match if both transactions have the same amount and their transaction dates are within a 90-day period. You might also need to manually select the right one if there are multiple matches.
If the amount of the cleared transaction is similar to the one in your register, edit the From and To dates to cover a longer period when finding a match. Please see these articles for more details:
Thanks for your quick reply! The checks are the exact same number and amount and are within the 90 day period. I attached a pdf with screen shots showing one check that isn't matching. This is just one check; it does this for every check for this client. I have other clients and I've never had this problem before.