You should be getting 1 checkmark ribbon for completing a Mystery Masterpiece Glory painting on Normal, 2 checkmark ribbons for Pro, 3 for Master. I checked here and it works for me. Not sure what you mean by the 3rd award...?

If you pause the game and bring up the menu while playing a Mystery Masterpiece Glory painting, you can see the requirements for winning the time, paint wasted and X's used ribbons.

Ah, the 3rd one was paint wasted. That's what I meant. When you start a new one in glory it shows the current awards number. I wrote down those numbers: 18, 85, 10, 43. I did some puzzles and checked afterwards and the first number (the checkmark one for completing it) did not increase unless I played the lowest difficulty in glory. The 2nd number (time, I believe) did increase. The 3rd number (paint wasted) did not increase even if I should have gotten it. The 4th number (Xs) is difficult to get on Pro but I got it on one of the smaller ones and it did increase.

Currently my awards numbers show: 19, 88, 10, 44.

I did some more experimenting. I took some screenshots showing before and after. I sometimes get one for time but I never seem to get any for wasted paint. And I only seem to get one for finishing (the checkmark) if it's one that is done in one space, not separated into sections.

I'm doing tests here and it seems to be working correctly. Maybe there's a misunderstanding about how ribbons are awarded? A quick summary is here

If it still feels like a bug, could you please send me screenshots of:
1 - The Mystery Masterpiece screen after you pick Glory and where you pick normal, pro or master. You should see your ribbon totals there. Pick normal pro or master and and play the level.
2 - Beat the painting. Take a screenshot of the plaque with the awards you won at the end of the level.
3 - Go back to the screen in step 1 and take another screenshot.

Ok, here are my screenshots.

#1 current stats : https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=556242001

#2 in the middle of solving : https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=556242129

#3 stats, paused in middle of solving : https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=556242254

Awards shot after solving puzzle : https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=556242889

Last, final stats after solving puzzle. Nothing has changed. https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=556243194

Also, I tried uninstalling the game, then reinstalling it.

Ok - I might have found something. The labels for showing how many Mystery Masterpiece ribbons you've won were being truncated to 2 digits. I just uploaded a new version that changes that to five digits. Give it a try and let me know.

That did the trick! Fixed. Thank you Dev!

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=556734163

Glad that was the problem!