iOS 12, Xcode 10.

I have two subclasses of UITableViewController, and the tableView of each has a row with a UIButton.
Both subclasses look absolutely identical (I have checked this in Xcode at least a dozen times) but still:
• One button works as expected,
• but the other one does not react to tappings at all (not dims for a short time, not sends its action methods). And yes: it has valid targets and methods. Doing sendActionOn: just work fine.
But I really want the button to react to tappings.

Where should I look for an explanation?

Gerriet.