Friend yesterday got it only after he finished 40 mission in total. After 25 and in game deed he start counting them on paper and after 40 mission he got this trophy, so this counter as well as almost all other including boss kill currently are broken and require to kill/finish more or don’t count some kill/finish.

They are looking into this. This is not the only trophy that won't unlock. I have 4 or 5 trophies where I got the requirements needed but no trophy. So you just have to wait till they fix this.

This trophy (stalwart servant) is glitched for me as well