I'm sure this is a combination of Amex and Quicken.
Tried adding a new account in Quicken Classic Deluxe (R65.17, build 27.1.65.17) by clicking the "
+", typing in American Express, etc. Login to Amex website. If I check ALL the boxes for ALL my accounts, quicken comes up with the list but does NOT find the new card account.
I then re-did and this time only checked the new card. THEN quicken finds it, but because the last 4 digits match ANOTHER (but DIFFERENT) Amex, it wants to link to existing, so I changed that to ADD to Quicken. However, then Quicken deactivates all the other accounts that were previously setup
OK, re-do yet again and check ALL The boxes again. Repeat the cycle (will not find new card).
So it seems I either get all but one account linked, or just the one.
Of course, the only way to get the new card # with Amex is to declare one as lost so you get one with a 2xxx instead of a 1xxx