TWRP and file based encryption, can't decrypt data

I can't seem to find a way to decrypt my data partition, thus making it impossible for me to do anything with twrp.
I'm using the latest twrp for the 5x, but it seems that there's a problem with FBE (file based encryption), after enabling it there is no prompt to enter a password/pattern anymore, and when booting into twrp it doesn't decrypt the data partition.

Any ideas?

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