If you think the invisible cards were odd...
I played a session of the Java version of Jacks or Better
VP at Golden Stars Casino (which uses the same software). I thought there was something strange going on as at times the cards in one hand seemed very similar to the last, but just assumed I was seeing patterns where there weren't any.
The screenshot I've attached from the log viewer (available for the last ten hands) shows I did actually get dealt the same cards at least once. I can't see any explanation for this except for the software having an extremely serious error in it. I also think at one point I was dealt a hand with a pair of Aces & held them, only for them not to be held when I drew.
I've exchanged e-mails with customer services & they're aware of the problem, though technical support haven't responded in the time frame they said they would. I asked for game logs of the session & they sent a word file which only showed whether I won or lost each hand. When I asked for a file which would let me see the individual cards dealt they said it was impossible
So, in summary, be very, very wary of playing with this software! (certainly if you're betting large amounts or not playing with a bonus)