On a Mac running Sonoma 14.4 if you go to save a template and a viewport on the template is selected, you cannot give the template a custom name. And, if you hit delete while the save template dialog is open (e.g. to try to clear the template name field) you will delete the selected viewport. Not a critical bug, but something to be aware of.
Hmm… works for me on 23.1 on Sonoma 14.4. Any other ideas on why this might fail? Was it a folder you can write to? Mine saved to “~/…/SketchUp 2023/LayOut/Templates” which is shortened for
" ~/Library/Application\ Support/SketchUp\ 2023/LayOut/Templates/". Try saving in another location?