This may or may not temporarily “fix” the issue. See here:
There are other reports or this issue as well, one just recently but I was not able to find it for this reply. I have not had the issue and don’t remember what was done to fix it. I have always saved my preferences so maybe I have found the answer or maybe not. Whatever. Something in the order of the icons in the tool bar (?), something in what is stored in the preferences (?) or what have you is causing a spurious gap to be placed in front of your first desired icon. You may have better luck going back to the defaults and placing your icons and order how you want them, then do a save of the preferences.