First of all, let me state that I don't have a complete picture of what is going on here, so this is all speculation at this point. I have some more variables to remove before coming to any conclusions. Just wanted to pose the problem and see if anyone else has had something similar and if they were able to correct it.
Running V2 wireless TX directly from DMX dongle. The problem has also occurred running the TX off of the DMX output of a smart string hub. At some point, generally when there is not activity, the LE's stop responding to the TX. The TX has a flashing data light, but the LE/RX's data light stops flashing. Range is probably 20 -30 feet, so that shouldn't be an issue. Both LE/RX's act this way when it happens, it's not just one. I've tried universes 1, and 2. I have not tried universe three yet, and I have not tried hard wiring the dmx to the LE's to be sure it's not the LE's themselves.
The only thing that seems to clear up the lockup is to first reset the TX, and then power cycle the LE's. Just power cycling the TX does not seem to clear it up. This has occurred when using both xLights and Vixen, but the only real commonality seems to be that it happens after a lack of DMX activity for some unknown time period. (i.e. I haven't run any sequences for a bit). It's happened after 15 minutes and it's happened after 24 hours.
The other thing that happens that may or may not be related is occasional "spikes". For example, using xLights tester tonight I had my blue strings on my mega tree on. About every 10-20 seconds, the green strings would blink on real quick. I've seen this before, but it was really noticeable tonight with only the blue on.