I'm using LOOL in its incarnation as Collabora CODE 4.0. Enter some text into a Calc sheet cell. Enter edit mode (F2) in the cell, select a word and press Ctrl-B or Ctrl-I. The word will be formatted using a bold or italic font, as expected, but the text cursor will disappear. It can still be used to continue editing or selecting text, it just cannot be seen any more, so you have no idea where it currently is. (If you're not keeping track *really* closely... ;) The only way I found to make it reappear is to stop cell editing and re-enter edit mode - very awkward if you're currently doing a bunch of reformattings for this cell... :-/
Mh, actually you don't need the hotkey, clicking the toolbar buttons while a word is selected triggers the same effect.
I get the caret back once typing again, but I can see the issue that simply moving the cursor after changing text properties as described. An interesting similar case in desktop: clicking into a piece of text and changing it eg. to bold changes it for the whole word, and also hides the caret. However, using the cursor keys to move it makes it appear again, and this doesn't happen in online.