Is there any progress on this topic? It also happens to me.
In fact, my problem is that some shares simply do not create the .recycle folder when deleting, and some only store the folders but not the contents. Others work as expected, but only sometimes. I have configured all the shares with 0 file size restriction and 30 day removal through the web UI and never touched any file by hand.
I have to say that all the sahres source from mergerFS filesystems configured with the official plugin, and most of them contain ACL configurations. I'm also running snapraid, but I don't see how this could be a problem.
Specs:
OMV 5.6.26-1
Kernel 5.10.0-0.bpo.15-amd64
Samba version 4.9.5-Debian
If someone needs more debug info to get more insight I can send full configuration files.