I've had this happen a couple times recently.
Normally I upload hi-def images, then resize them down (by double-clicking on the image and changing the size). I generally will downsize multiple photos to 340/360 width while maintaining the aspect ratio so I can fit 2-3 photos in a row.

For single photos I will often resize them to 640-720.

But the last couple of times I've uploaded pics, stuck them in a post and resized them, after I've clicked "submit post", the software sets the pics back to the size they were when I uploaded them. This didn't happen before the last software update (that I recall at least) but seems to be happening all the time now.

I've tried editing my post(s) to resize the photos again and, again, after I've saved the edit, the photos are back to their original size.

Just did it to me again a couple minutes ago.

I know from my own experience that a lot of people don't like opening a post (or scrolling down a thread) that's full of full sized photos, especially if they are on a smart phone. That's why I always resize them before posting. Makes it easier for those who just want to scroll past whatever I've posted (so they can post a one or two word troll afterwards).

 

That has been reported before. I noticed that happening on first day after the upgrade. I used it a lot to resize images that were posted. 

If I want them smaller I have been resizing the images before posting them.

It seems to have been fixed as I posted some photos today, resized them in the post, submitted the post and the pics didn't change back to their original size again.

Test:

 

Sadly not for me, just tested a pic (deleted on edit) and still same issue.

 

Test:
492                                                                                                                                                 246
    


421 x 600                                                                                                                   210 x 299   
      

 

Well darn, that didn't work.

I left the first pic at original size and set the 2nd one to half the size but after posting, they are both the same size.

Just went back to the other post I'd made earlier and yeah, they had reset themselves to their original size as well.

(Time to start posting drunk again as I can't seem to see straight when I'm sober !)