Hi Rom, glad you found the problem, hope it helps someone else.
I have found the way to fix my problem: it was due to Greenify wakelocks cut-off function, name of the wakelock for the Google Play Store app wich we mustn't block:
"com.android.vending.billing.InAppBillingService.Bin {com.google.android.finsky.billing.iab.InAppBillingService}"
After that, i have test to send an empty "a.ixc" file through Bluetooth, but i get an error 2 times.
In Bluetooth Toolkit app, i have enable the two options to allow all files and the second one to allow even unknow files.
I have do this test:
from my first device to my second one
from my second device to my first one
I can't even send the logfile from xposed installer apk through Bluetooth.
I have attach it here, i have take it from my computer with USB.
For what you have reported sadly I didn't find a way (yet) to SEND every file type, but if you use a device like your pc, the phone should RECEIVE it fine (test and report me if not). I also found a minor bug in your logcat that I will fix in the next version, but this is not the culprit. Feel free to PM me so we don't clutter the thread too much!
EDIT: Could you also share with me your bluetooth apk for further testing? Thank you