Hello, So I have experienced this in the main game. What usually happens when I alt Tab is that it Resyncs the whole game causing other players in my game to resync. This Bug (For my laptop) is to me gamebreaking, no its not that it has to resync (part of it) Its that it will only resync when i go back to the game. I am not sure if this is just me or its happening to other people. I just hope that it will be resolved in the beta or sooner updates.
PC SPECS
Processor Intel(R) Core(TM) i7-6500U CPU @ 2.50GHz
Video Card Intel(R) HD Graphics 520
Video Card #2 NVIDIA GeForce GTX 950M
RAM 12 GB(DDR4)
Operating System Microsoft Windows 10 (build 15063), 64-bit
Not from Ubi but work in tech.
I can hypothesize what is the problem from your specs. You are most likely playing in fullscreen mode instead of borderless. When you alt+tab to desktop your computer switches off the nvidia chip and starts using the intel chip to save power. This makes the game engine start going nuts thinking your computer has problems. You could easily fix this by playing in borderless fullscreen mode.
Thanks for letting us know! It will help if you can also report the alt-tab issue with us here