Cannot digitally sign PDF's while FIPS mode is enabled.

Our organization cannot digitally sign some PDF's while FIPS mode is enabled. Newer PDF's using newer hashing algorithms can be digitally signed, but I'm assuming most of the PDF's our organization sees/uses have older hashing algorithms. When FIPS mode is enabled, this prevents our workforce from being able to digitally sign those PDF's. Can PDF's that cannot be digitally signed while FIPS mode is enabled be updated in some way to allow digital signatures?