Quote:.... I noticed a similar development. Sometimes the FUZZY tool would work....sometimes.
And, when it DID work....the "marching ants " were not visible.
garystan
First, according to your profile you are using Windows, so that problem for OSX does not affect you. Fuzzy selection not working ? You need to give details, most often user error, however.
If the selection is not showing, (1) You might have inadvertently turned it off. keypress CTRL-T see View -> Show Selection. (2) A 45⁰ degree selection line does not show because of the way the 'marching ants' is rendered.
If either of those happen, ways to display an active selection.
The selection editor dock. Windows -> Dockable Dialogs -> Selection Editor
The Quick Mask Select -> Toggle Quick Mask or Shift Q or the toggle button bottom left of Gimp window. This is used for painting in a selection but you can toggle on/off to check the selection.
A layer mask from selection. If you are going to delete (say) part of an image the layer mask shows the extent of the selection. That toggles on/off as well from the Layer -> Mask menu.
You are obviously not happy with Gimp, maybe try an alternative, there are plenty around. Do a search. examples: https://www.lifewire.com/free-photo-editors-1357098