I think that I've finally solved the issue with image upload size restrictions for all users. I've tested this fix by assuming permissions of a regular registered user and it allowed me to upload a 3.9 MB image file with dimensions of 4032x3024 pixels, which the board correctly thumbnailed to an appropriate size to display inline.
Users are welcome to test the new permissions and report back here. Thank you.
Users are welcome to test the new permissions and report back here. Thank you.