I had this exact conversation about 9 months ago.

Credit Ninja: "Mr. diljs you have over 30 open accounts!" (of which 7 at one point were with Chase, only one remained)

We went back and forth about whether this was risky or not and eventually I offered to do a one to one swap of closing a card I had with Chase, and Chase giving me the new card with the same limit as the old one. Despite the complete lack of any added risk, the Credit Ninja kept repeating things she'd said earlier and wouldn't do it. This happened with a couple of other apps in the next couple of months.

The fix: I waited a full 6 months before applying for more cards and suddenly I can get new chase cards again. That "have you been denied credit from Chase in the last 6 months?" question on their apps was the clue. Whether you check that box or not, it seems applying again 6 months after a denial automatically gets you declined.