Same issue here, BOOX Note Air 3c. 0nly happens in Obsidian.
Another workaround of sorts is to use an external Bluetooth keyboard. I am using a Logitech K480.
Also, I notice that the Google Play Store says that version 1.5.12 (March 30, 2024) “Fixed typing issues for some keyboards and voice input.” Perhaps those fixes broke something.
I have been running Obsidian just fine on my Boox Tab Ultra C Pro on build 2024-03-27_12-55_3.5.1_bc68f4065 until today when I updated obsidian to 1.5.12 and I am now experiencing the same issue described/shown in this thread. The fixes suggested (floating keyboard and physical) both work.
I have the same problem with Onix Boox Note 3. All other apps work flawlessly with any keyboard, only Obsidian present this annoying problem. Hopefully someone will come with a better solution; Obisdian is my most used app, without it my tablet is basically useless. 
Same problem here with a Boox Note Air 3c. The small floating keyboard is really anoying to work with. If someone need a beta tester, please contact me.
I just received my Boox Note 3 and I’m having the same issue with Obsidian
I was hoping this issue would be solved with obsidian 1.6.3
It is not, unfortunately.
I use the floating keyboard, which is horrible and small.
Hi everyone, I was also really annoyed by this bug. So I asked the support (through feedback app) to be enrolled in the beta program. I got the upgrade few hours later, and this bug is solved on it 
Are you talking about Obsidian’s beta program or Boox’s beta program ?
Boox’s beta program, you just have to ask in the feedback app 
Although I think some might fear possible bugs in a beta version, I encountered none yet
Anyway, if it’s fixed in the beta, it shouldn’t take too long to get to the stable version
Thanks for the tip. I reported this issue to Boox as well but they never suggested this to me. As you can imagine, this bug is a total show-stopper so I’ll ask them to add me to the beta as well.
The official stable update from boox came out today 
problem solved
Which device do you own? For my Note Air 3c is no update available
I have both a NA 2+ and a NA 3. None has received the update, but if you go the the Update history on the NA 3, it appears as I had received the 3.5.3 update already. I guess it will be a matter of few days before we got it. Strangely, my NA 2+ is not affected by this keyboard issue on Obsidian, only my NA3.
Now that the keyboard is working, the Toolbar is not showing at all, making it very difficult to add internal links or do a simple undo… Anyone having the same problem? Note Aire 3 (Note Air 2 +, again, not affected).
Same issue here. I bought the Note Air 3c three weeks ago, and updated the firmware to 575390d56. Since then, my keyboard does not work in Obsidian anymore, but in every other App it does. Do you know if this will be fixed?
I have this issue as well. I just got my new Boox. All firmware is up to date. I just installed Obsidian. The keyboard flashes for a moment, then vanishes. Please help.
How can I be sure I’m on this release? It says my Boox is up to date, but I still have this issue.
I am still having this issue after wiping my tab ultra c pro. Even tried installing older Obsidian versions to no avail. My boox has been saying its up to date for months even though they announced the new firmware…
This issue has been solved with the latest Beta update (3.5.4). The toolbar now appears above the keyboard 
Which device do you have and which update version are you using?
I have the same version as @dboucher and it’s also not working
Onyx Boox Note Air 3c
Firmware Build Number: 2024-03-27_11-06_3.5.1_575390d56