Hi,

I suggest going on this way:
  • disable the stream sense and try to reproduce the issue.
  • (with stream sense enabled) place a sleep of a couple of seconds between the openConnection and the subscribe call and try to reproduce the issue
if none of the above reproduced the issue, then you're probably experiencing our bug, otherwise the issue should be somewhere else.

In any case, if possible, attach here the server log showing one of the sessions that had the issue.