Hi @joshmule, welcome to the forum!
The 7z problem is still present.
We can use external tools like that, but for compression it is a bit problematic. Duplicati needs to get feedback on how large a file currently is, so we can make sure that the files do not grow over the requested volume size.
Normally, the commandline tools take an input and produce a compressed output file. We need to keep updating the output until we reach the file size.
If something like this is possible with an external binary, we can use it. Otherwise it will give sub-optimal results.