I was a California Resident serving as active duty military in North Carolina until July 20th, 2019. When I got out of the military on July 20th, I remained in North Carolina, working, and am still he

You would be a part-year resident of CA and part-year resident of NC.

Your CA residency lock that you maintained while in the military ended when you separated.  Your separation date on you DD 214 is the date you became a NC Resident since you remained in NC to live and work. 

Normally, a military person has something like ~120 days (+ or - 30 days) to reestablish themselves in their home state without changing their residency...but if they don't return to their home state, they become a resident of whatever state they settled in after they separated service......you've settled in NC, at least for tax purposes.

On the MyInfo page (Online software.   for desktop software it's the "Personal Info" page) you will indicate you were a resident of NC on 31 Dec 2019, and that you "moved" from CA on the date of separation from the military  (YES, you lived in another state in 2019...that's CA while in the military).

Fill out the entirety of your Federal tax return and all its data...income..dividends...interest...and a deductions & credits...every scrap.   Then, start in on your CA and NC part-year tax returns...each will have you indicate what subset amount of various incomes belongs to each state...  Your military income and all income before your military separation belongs to CA..  Everything after belongs to NC.

Not sure how CA works, but NC uses your entire Federal income, with various adjustments to get a full-year NC taxable income on line 12b of the form D-400, then it reduces that amount by a decimal multiplier (line 13) that represents the fraction earned while you were actually an NC resident to yield the final lower NC taxable income (line 14) for you.   But the decimal in line 13 won't fill in properly until you go thru the entire NC interview to allocate what parts are NC income, and what are not.

Generally, if your military wage, and your NC job wage are about equal, the decimal in line 13 should be around 0.5  , but that does depend on what other types of income you might have had during the year and which state you "allocate" those $$ to in the interview.