Tasks queue bug

From my understanding, the task queue works like this:
It first follow the categorized priority (e.g. researching, building, digging), then under that priority tier, it follows the numbers ( 1 - !! ).
Today I came across 2 bugs when adding tasks.
1.) The first game, I gave a duplicant a digging and building job, which requires the duplicant to dig a block and place something there.
I have that both digging and building at top priority for that duplicant, and set the task to !!.
It was never added to the queue, until I cancel the task and manually add a digging task first and do the building task later.
Not a good experience, but it didn't break the game.
2.) I set researching to top priority for a duplicant, it has the orange researching hat and set research target to Distillation.
However, when it reaches 30/30 on Novice Research & 12/20 on Advanced Research, the duplicant can't continue the task anymore and just went idle.
I tried to switch the research target, the duplicant finished them on both Novice and Advanced Research.
So I switch back to Distillation, it went idle again.
I check the task queue. Idle.
This breaks the game.
Now this save is f_ked up with no water filter.