I asked this question too 9/4/2020.
Never got an answer from Adobe.
I'd also be very interested how to handle this.
I guess the main issue is ecid's.
My suspicion is that you need to merge ECID profiles somehow manually into a new dataset (?) and delete the original entries.
Hi, You can not access the Profile in the UI. But you can open the identity graph by exporting the failed batch. In the batch, you should find the IDs and look these up in the profile graph. Currently I don't know if there is any reasonable approach besides removing the ecid upon logout.