New files that are created via Windows Explorer are possibly not appearing in bash because they are missing special LXSS NTFS attributes.
When LXSS creates files in the LXSS root, it attaches additional information to them via NTFS attributes to store things that cannot be represented by the standard NTFS attributes, such as Linux file permissions. If these are missing, it the files don't show up.
This is supported by the fact that if you make a file in bash, and then make a copy of it with Windows Explorer, it appears in bash. This is presumably because all of the special LXSS attributes were duplicated with the file.
The LXSS filesystem layer also appears to cache the file system, so the directory entries in bash will not reflect the actual state of the file system if files are added or deleted until all bash terminals are stopped (which ends the LXSS session in the LXSS service and hence clears the cache).