What I would recommend doing is to restore your factory default settings and see if that fixes the issue you’re experiencing. This can be done by going to ‘Extensions > PlusSpec > Restore Factory Default’ and then select ‘Yes’ in the pop up that appears.
Would you be able to please let me know if this fixes the issue? If it doesn’t, can you please send an email to support@plusspec.com with a model with the issue and a screenshot of the dialog options you’re using. Can you also copy & paste any error message that appears in the Ruby Console into the email (go to ‘Window > Ruby Console’ and then replicate the process to get the issue).