I completed campaign 3 and then a scenario. I did not receive a star next to the name of either. But the exisiting stars I have for campaigns 1, 2 and several scenarios still exist, (I completed these with the previous patch).

Is this related to the difficulty setting, (I always select hard), or is this a game bug?

Here's a quick way of reproducing this bug.

Delete 'complete.bin' or have a fresh install of Massive Assault.

1. Play scenario 1 "Ambush".

2. Win.

3. Return to main menu after winning.

4. Notice you have received a star.

5. Play scenario 2 "Amphibian Assault".

6. Win.

7. Return to main menu after winning.

8. Notice you did not receive a star - Game Bug!

Could someone confirm this problem?

Noticed the same thing. Also noticed that I had scored 0 for beating it. I figured that I didn't beat it 'well enough' or on a high enough difficulty. Developers?

the problem is we have remade only original 24 scenarios from version 189 not additional scenarios from the web.
But we are thinking what we can do with this.