I also use k9 mail in the personal area on an Android 16 smartphone but I can no longer attach files present in the personal area itself.
What do you mean with personal area?
Also, which exact version of K-9?
Can you describe the behavior?
The more information the more probable that someone might be able to help.
My phone is a Samsung Galaxy 25 Ultra.
The personal area is a secure folder used on Samsung Galaxy.
The problem arose after updating to Android 16 some week ago.
K9 is 12.1 version
I can no longer attach documents from the same secure folder but only from the folders outside the personal area
A quick google suggests this is a bug with the file picker on Samsung phones running OneUI 8 on Android 16. Users report other apps being affected so a fault with K9 is unlikely. See link below.
https://www.reddit.com/r/oneui/comments/1o4oxf1/one_ui_8_android_16_update_broke_secure_folder
Thanks. I hope Samsung fixes this bug as soon as possible