Some time ago, I reported bug 2118 (https://bugzilla.samba.org/show_bug.cgi?id=2118), and in the course of checking up on the functionality again I've noticed that there still seems to be a problem, which seems to be different enough to warrant a new bug.
Basically, I have the following set in several of my shares:
ea support = yes
store dos attributes = yes
vfs objects = streams_xattr
When samba is restarted, the attributes work fine. After a short period of time, they stop working. A restart and the pattern repeats.
With the logging cranked up, the time seems to take longer. It may just be perception though as things are noticably slower with log level set to 10 :) With the log level set to 3, it takes a few minutes to happen.
My test case is a directory with a "desktop.ini" file present with the hidden attribute set. Restart samba and refresh the view. The file is hidden. Wait for some time, and hit refresh again. Eventually, the file will no longer be hidden. Bringing up the file properties will show no attributes, and attempts to set them will be ignored.
I've experimented with trying to prod the server with other file accesses to other file attributes to trigger the loss of attributes, but it's all so circumstantial I can't say anything concrete.
When it gets to the point where "attempts to set them will be ignored", crank up the debuglevel on the smbd to 10 using smbcontrol, and then add the log (and wireshark trace) to this bug report please.
It seems I had another issue. Despite several attempted restarts (to get the logging you requested), I had some smbd processes hanging around that weren't going away. I had to kill those and after a restart of my client I'm not seeing the behaviour. I'll reopen if I start seeing it again.