Pandemic Puzzle

No glitches, no hangups, no controls doing what they shouldn't. Seems to be perfectly solid in terms of construction.
There do seem to be some issues for me when it comes the game states. In something like Minesweeper (which you mention) the game state is always the same: You have uncovered tiles, covered tiles, and all the information necessary to tell what surrounds the uncovered tiles. Thus your purpose at any time is to determine what is under the covered tiles and uncover them if they are safe.

This game doesn't have a state like that where I can know for sure what I'm doing.

• I first thought my purpose was to keep all of my units healthy but with random hidden diseases this is purely luck until I hit one and the unit coughs. (Consider having a limited number of cures at the end so the first expected sick units are forgiven and the player isn't punished unless they play poorly and get further units sick).
• Then I thought my purpose was to keep the number of sick units low by keeping the healthy ones off of sick trails and not putting them adjacent. Unfortunately the win condition is all units adjacent at the top so as long as one unit is sick they will all be sick, as masks are infrequent and rarely a viable option, so I might as well brute force all units to the top when someone coughs just so at least no one dies. (Consider having the top be ICU beds or something so units "lock in", can't move but also can't pass on the disease when they hit the top. Or maybe some units are medical professionals and are always equipped with masks and you need to use them as a wall to 'quarantine' sick units from healthy units at the top).
• Then I was confused as the only win condition seemed to be never hitting a virus which ended up happening a lot as if I found a single safe path to the top, all other units could follow it and be guaranteed to be safe. (This is a bit more of a doozy to fix. You have to let units interact with each others' paths otherwise each unit is just a random chance to get infected moving in their own space, and you can't change the board state to possible invalidate a safe path because then all motion on the board is random chance to get infected).

Dealing with the disease is the main mechanic but without the information of someone being sick there is no information at all. You don't start interacting with the game mechanic and planning movement until symptoms show but symptoms showing means you've gotten closer to the failure state (all sick or dead). Getting the best score (no one sick) isn't something that can be achieved by smart play but purely by luck (finding a safe path to the top).

As a classic thinking sort of game like minesweeper there is too much randomness that can affect your score and too great an emphasis on fast thoughtless movement at the moment. You have a solid base, though, so with more iteration you can definitely clear that up.

Good work so far, looking forward to what comes next!