i have same issue, but i find a way works for me,u can try this:
- use develop provision and distribution Certificate to package the ipa
2.use UE_4.21\Engine\Binaries\DotNET\IOS\IPhonePackager.exe , in "advanced Tools"tag, “re-sign an ipa”,use your distributeion provison to re-sign your ipa, this final ipa is the right ipa you want