Calc: Form controls disable cell entry, and break calculations

LO v7.4.2.1 on OpenSuse 15.3
I added some form controls to a sheet in Calc; now, after I use the control (select, set a value, RTN) it disables cell access/ data entry. Formulae update, but I can’t edit cells, either in the formula bar, or in- cell with double-click
‘Open in design mode’ is off. I manually turn design mode off, in the Form Controls toolbar.
Also, keyboard shortcuts and function keys (e.g. F4 : cycle cell ref) don’t work.
I can invoke the Function Wizard, or the function select (next to formula bar), after which cell editing is again possible.
Please help me make it stop! When did this become difficult? There’s no obvious sign that’s it’s in some weird ‘editless’ mode.


P.S. I’ve just noticed that cell comments also get stuck as visible - I need to click ‘show’ and then Hide’ to get them to disappear.