This sounds a bit strange, I have not come across this before.
If you are using a child theme, please switch to the core theme, install the plugin then switch back.
If you are still having issues, please set your reply to private and provide your URL/login details so I can take a further look for you.
Not for the above as it just randomly installed, but I recommend downloading the plugin from here > log into your site via FTP and remove the plugin folder > Upload the one you just downloaded.
If you are still having issues, please create a new topic and set your reply to private and post up your WordPress and FTP details. I will then look into this for you.
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