Cannot decrypt universal ipas

[ego-lay-atman-bay]

There is a thing called ipa thinning, which is just ios stripping the 32-bit binary from the ipa (or the 64-bit binary on a 32-bit device). I have installed a universal ipa, which is not thinned, but when I try to decrypt it, it says it's decrypted, but the resulting ipa is still encrypted.