Need word similar to 'fixer' but for a legit professional context

Solution 1:

From Thesuarus.com:

Troubleshooter(n): One who finds and fixes issues or problems.

This is LRWerewolf, our number one troubleshooter.

Factotum(n): Jack-of-all-trades

And from personal insight:

Facilitator(n): One who makes things easier, or just makes them happen.

I'm the facilitator for the department; you need something done, I can help make it happen.

Solution 2:

Also consider

ex·pe·dite ˈekspəˌdīt/ verb verb: expedite; 3rd person present: expedites; past tense: expedited; past participle: expedited; gerund or present participle: expediting

make (an action or process) happen sooner or be accomplished more quickly.
"he promised to expedite economic reforms"
synonyms: speed up, accelerate, hurry, hasten, step up, quicken, precipitate, dispatch; advance, facilitate, ease, make easier,

further, promote, aid, push through, urge on, boost, stimulate, spur on, help along, catalyze, fast-track "our legal assistants can help expedite the paperwork"

This is most often used with reference to project management (see https://en.wikipedia.org/wiki/Expediting) but might be useful for your purposes.