I had the same issue and it's extremely annoying. Resizing seems to help most of the time.
Now, I usually make a post on the web browser then go on tapatalk to edit the post and upload the photos. No need to resize them and it works quick and easy.
Forum software. It's been an issue for about a year. We lost our imbedded resizer.
Downsizing your pics on your own before uploading them fixes it in most cases.
Tapatalk uploading seems to work well, too.
The forum software never had the ability to rotate pictures. It can't read the EXIF data to tell what the orientation is.
The issue with size for the last year is due in part to cameras taking bigger and bigger pictures. Again the forum software was never designed to handle the size that cameras can now take.