'In the Lead By A Quarter Nile' achievement not unlocking

As title says, this achievement is not unlocking despite fulfilling the conditions. Steam, latest release (9.1.404). Twice on easy and once on intermediate, I have fulfilled the achievement’s conditions, controlling all control points in the Into Egypt campaign scenario at the same time. Achievement should unlock but will not. I have confirmed that at least before the latest patch, it unlocked for others playing on intermediate as soon as the ninth control point was captured. It will not do so for me. Perhaps the latest hotfix has changed something?

Edit: I tried again this morning on Story difficulty. Gained control of all nine control points. No achievement. Lost one, regained it. No achievement. Lost another one, regained it, no achievement. Scenario ended, no achievement. Just as with my other attempts.

Edit #2: This achievement finally popped for me, on the next map, at the exact same time as “Master Naval Trader” (my very next achievement).