Not fully understanding what you are saying here. Release 5.33.6 is probably the best-functioning SBIE build I've ever used and I trust it implicitly. This is the final Sophos build and can be downloaded:
We are happy to say that we have made some progress towards making Sandboxie an open source tool. We are releasing an updated version that will help us prepare for
community.sophos.com
One might need to fill out an Export Compliance application, which isn't much to do. I was able to get the 64 bit installer again just now. Works great for me on Windows 1909 but poorly browser-wise on Insider Fast ring builds 19603 and 19608. I'll have to wait.
One can read the SBIE developments starting
here. It seems a former Sophos engineer with expertise of the SBIE kernel will be volunteering his time. The Sandboxie authorities are suggesting to stick with 5.33.6 for now, instead of open source 5.40.1 due to a certificate issue.
I've sandboxed Windows MP3 player w/Sandboxie myself, no problems at all. If you want to explore other sandboxing software, there's
Shade which I have tried several times and found it not to be friendly. But that's my opinion.