Photo attachments have zero kb file size

For the last month or two, I’ve been experiencing a problem intermittently, with no rhyme or reason.

When I attach 4 or 5 photos to an outgoing email, 50% of the time the recipient will report that the photos arrived with a file size of 0kb. The original photos are approx 1-2mb each.

When I view the failed email in my sent items folder it also reports zero file size, which leads me to believe that the issue is in k9 mail, NOT my mail server

I’ve tried sending from Wifi only, from cellular data only, attaching 1 file at a time, VS 5 files as a group - waiting a full minute after adding attachment, before sending - but I can’t find a reliable way to ensure that the attachment sends properly, every time, nor can I replicate the issue on demand .

The issue only happens when sending from my cell phone via K-9 Mail. The same email address is attached to my windows outlook mailbox - and never has an issue.

Is this a known issue?

Phone samsung s23

Android 16

K9 mail version 18