We have a standing thread for post testing. It’s in the Site Feedback category since that’s where we put threads about the Discourse technology, not about the SDMB moderation or rules or TPTB, which go here in ATMB.
Here’s a pretty good commentary on image posting. Note that the various tricks needed to outsmart various image hosting sites’ desire not to let you post a pic directly change over time. And vary betwen PC, Mac, Android, and iPhone. ISTM mobiles try hardest to make sharing “easy” in a way that really stymies your actual goal.