Hmmm that kind of makes sense.

I think (and this is just a wild guess, could be I am totally wrong here) that these "aegisfs" mounts are done via FUSE on top of the base file system.

If the mount fails because the base file system under is already a FUSE mounted fs, like encryptfs here that would suggest that FUSE systems cannot be stacked on top of each other.

I really am not sure if this is the case? I kind of assumed it is possible but if tis turns out not to be feasible I will have to rethink my architecture.