PPT 365 - Lock option not present in the Selection Pane

After the latest Windows update the PPT Selection Pane lock option has vanished.
I'm really stuck with all my projects.
Anyone else with the same problem?

I've not had that problem with my 365.

I can lock / unlock from the Right-Click menu from an object and also via the padlocks in the Selection Pane.

It's not a function I use very much, but one that I could probably make better use of.

Problem solved: magically the lock option reappeared.