Did both of those applications result in a hard pull inquiry? If so (and possibly regardless), i'd reach out to the bank and ask them what other ways can you provide POI. If no other options, i'd probably abandon their card and go with a different product - one that offers a prequal.
Unfortunately, some institutions can only accept tax return information. So copies of bank statements or payroll stubs in most cases will not suffice.
As mentioned above, you can try reaching out to them to determine whether other alternatives for POI are acceptable, but if they won't budge then not the end of the world. Try a different CU or lender.