I think this bug has already been reported by some user but Ashley said it was due to some aspect of the connection.
For example, I remember that a user who tested in the institute and he had this error.
I have wifi connection and also I have this error.
https://www.scirra.com/forum/multiplayer-players-turning-invisible_t101268
That is a pretty old report if you'd ask me, I highly recommend you to create a new one with all the ways to reproduce.
From my experiences with the multiplayer plugin, I can tell that I've never had issues like that (I only use NW.js though).
Besides the emulated testing, I also did some heavy tests with multiplayer by myself with cases like:
- Playing with people from oversees, latency very high (500+) & high loss rate
- Syncing up a huge load of sprites at once
- Playing with 5+ players with huge differences in terms of the client locations
I've never experienced any issues, I'd admit that it got pretty "choppy" sometimes but the plugin
got itself together fast most of the times and synced all up well again.
(For some reason it always felt as if the plugin worked better with higher latencies than with lower ones.)
So I'm ready to test it out as soon as you made a report and I guess Ashley will do it too.