I spent quite a while looking for a 'fix' for my Epson V300 and couldn't find a solution...... until now.
Using the Windows Scan app certainly works for scanning documents and photographs but not slides and film which is why I bought the V300 as it could scan all that I wanted it to.
When I reverted back to the Epson program, it only allowed the scanning of documents, so I thought "Well at least part of it is working".
Then I clicked the drop-down menu under 'Mode' and chose the 'Professional' mode and hey presto, it gave the option to scan films and slides.
However, the 'preview' and 'scan' buttons were missing.
Then I read somewhere recently (thankyou to that poster) that if you click in the grey area above the 'Help' 'Configuration' and 'Close' buttons, the preview button magically appears! Then the scan button appeared after the preview scan!!!
Wierd I know, but I think it may have fixed the issues I had, and I hope it works for you too.