Civ6 cannot combine units into corp

I have the nationalism tech which allows you to combine two units of the same type into one stronger unit.

The problem is I am not able to. I have positioned 2 crossbow units, both with full health and full movement next to each other but I don't see the option to combine them.

Is there some other tech or requirement that I need for them to be combined?

I have tried combining 2 lvl 2 units, a 0xp and a lvl 2, and other combos of my crossbow units but I don't get to combine option showing up.

I can take a screenshot too if needed. Thanks

UPDATE: Once I reached mobilization ( which allows 3 units to be combined ) the combine into corps button showed up. For some reason I just was not able to combine any troops before that. That also means I couldn't get the inspiration for the mobilization civic either ( which was to have 3 corps in my army at 1 time.) I even made two brand new units and still was not able to combine them. I am playing as Gandhi as well, but I don't see anything about him that would prevent the Nationalism Civic from working.

It seems to be an issue with the last update of civ 6 - in the past it was definitely possible to combine two units into a corps as soon as one got "nationalism" - now your are only able to build corps in cities, if a military academy is present in that city.

I am not sure whether that is intentionally done or it should be considered to be a bug.