Very Odd. Two things come to mind. 1) Once we enter the realm of "Well, that's really weird", the 'go to' suggestion is to reset your preferences file. Also see: https://www.lightroomqueen.com/how-do-i-reset-lightrooms-preferences/ To do so, hold down Alt and Shift (Windows) / Opt and Shift (Mac) while opening Lightroom and it’ll ask whether to reset the preferences. The timing is crucial—hold them down while clicking/double-clicking on the app/shortcut. Note - this will put all your preferences back to the Adobe Defualt settings so you'll have to reset them to your desired values afterward, The preferences file includes last used settings, view options, FTP settings for uploading web galleries, some plug-in settings, etc. In case it doesn't fix your problem, you may want to make a copy of your preferences file first, so you can put it back and not have to re enter your desired changes. Alternatively, you can reset the preferences manually. Moving or renaming the preferences file, rather than deleting it, means that you can put it back if it doesn’t solve the problem, to save you manually recreating your preferences again. See link provided above 2) You may have a stuck key on your keyboard. Make sure that all the key are not stuck in their pressed postion or try a different keyboard if you have one. You can also go into a text editor and verify that all the keys are working properly although verifying the Alt, Cmd, and Ctrl keys may be tricky.
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