Word for thought process debilitating productivity

Solution 1:

Possibly "obsessed", "fixated", "preoccupied", or maybe "prepossessed" fit your description of thought processes that limit other thoughts or productivity.

https://www.thefreedictionary.com/obsessed

https://www.thefreedictionary.com/fixated

https://www.thefreedictionary.com/preoccupied

https://www.thefreedictionary.com/prepossessed

Solution 2:

I suggest distracted which according the the Oxford Dictionary is an

adjective
Unable to concentrate because one is preoccupied by something worrying or unpleasant.

One example given is

These days I'm so distracted by the arguments over it that I cannot concentrate on teaching my students.