So I tried testing out using a balloon animation and didn't experience any freeze. You may wanna test to see what other plugins could be causing it.
I have the same problem. I disabled all other plugins and the problem persists. All I have enabled are MZPlus and MZPlusPrimeParallax. With both enabled it wont show balloon-icons. With only MZPlus enabled, the balloon icons are back. (game doesn't freeze, just for the second where the balloon animation should actually be shown). By the way, it is really an awesome plugin, which does exactly what I wanted :)
I just made a new project with only the mz-plugins. All is ok. So I started a new game on the firtst project and now it works with even a lot of other plugins. But it won´t show balloons on a save game. i test a bit more later because its 1 am and i have to get up in 4 hours. will be back on testing after work
I tried a lot of combinations with different events on a new project and the project where the ballon-ani was missing (from the start, from new saves and I even made a save on the same position as last time). I was not able to reproduce this issue. Only on the saves from the first project. and even there it´s only missing on the player char. The balloons are all ok on other events. But on the player it is not only the balloons but all animations. So maybe it only occurs while actual building the game, installing, deinstalling and testing things out, because on the new saves the plugin was already there from the start?