Currently, debian-sources-lts 4.9.130 does not support use of fuse FS inside lxd containers, due to missing functionality. The missing functionality is implemented in the patch referenced below:

userns for fuse in kernel 4.18 here is the pull request
http://lkml.iu.edu/hypermail/linux/kernel/1806.0/04385.html

this currently disables use of any fuse fs inside container.