@embeddedmz , did you try to follow this instructions?
https://forums.ubports.com/topic/6951/ubports-quick-and-simple-install-on-xiaomi-mi-a2
I was in same sittuation, phone I bought had Android 10 but I downgraded it following tutorial I linked above.
@TheBird , yes. I noticed same - I though however to look for information if anyone knows how to fix it without workaround like that.
I will live with that for now - thank you a lot.
This guide worked well for me.
Unfortunately I could not install Ubuntu at the end ( installer was getting <waiting for device> error due to fastboot crashing after downgrade to Andreoid 9). On some other articles people were suggesting it could be USB Port issue, that may be true actually. As I had no other idea I installed "installer" on other laptop (switched from Ubuntu to Mac) and there it worked..
@embeddedmz , not sure if root cause is same but I had same problem. On other chat I found some people saying issue could be in USB 3 port. I switched from my Ubuntu laptop (which I experience problem at same stage) to Mac from 2015 and ubports installer managed did the job there 
not sure if that helps..
@embeddedmz you are correct. I see same after reading your reply.
I am not able to say if this problem came with recent ota-21 update as I did not use BT before but niw I,see same problem you describe (including toggle goin back to disabled)
@TheBird , yes. I noticed same - I though however to look for information if anyone knows how to fix it without workaround like that.
I will live with that for now - thank you a lot.
@lduboeuf , thank you. Unfortunately for me it appears after phone and/or waydroid reboot. I think I even uninstalled waydroid via helper (due to other problems) and it did remain.
I noticed something that I think is a bug of Waydroid Helper (Ubports 20.04) which I did not see in past (16.04)
When I go to section about hide/show apps, I can not hide any app. Each time I swap right and icon of trash appears, when I go to next app on list - previous one reset to default state.
Pressing 'trash' icon does do same (nothing)
I can reprodue it now but printing of 'waydroid log' does not tell much (it actually says that 'stopped' while I am interacting with any app (lik DuckDuckGo) , no exception is printed.
Hi all,
I recently installed UbTouch 20.04 on 2 phones (OnePlus 5, Pixel 3A) and I noticed that Waydroid is not stable.
I try t odescribe observations but not sure if this is 100% accurate.
I use apps and I notice at some point an app does not start anymore (appears in launcher but not on screen).
When I took 3rd phone (Xiaomi A2) and updated 16.04 to 20.04 (also to stable one) I noticed similar regression.
I think, Wayroid Stop helps but I am not super sure yet as on Xiaomi Waydroid helper started hanging each time when I want to run it (to add Stop on screen)
@taiga-woods (all), If you look for great battery life experience, I can tell that I also have UT on Xiaomi MI A2. I do not use it much apart of reading news each evening but device (connected to wifi all the time) stays alive for 100 hours and more. Just FYI 
@martinm , I confirm what others said. I recently bought Nexus 5 in order to install UT and I tested battery for a week to know condition, it was able to run (idle) for 2 days while on UT it is max 12 hours.
@bogotrax please disable wifi before starting waydroid. If all works on cellular data for you (does for me)I would call it known problem reported in other threads mi a2 related...
@branja6 did you managed to have UT at the end.? Thread is old and I see no XA2 on official list, so I guess it was not ported?
Thx