Incompatibility problems with Pay with a like and WordPress Themes

Hello,
Pay With A Like use to work perfectly for years on my website. For some months now (I think after an automatic update of WordPress), it is no longer the case:
- it is still possible to like via the PWAL buttons, but the secret content no longer appears.
After deactivating all the extensions (no change), it appears it might be linked to a theme issue. When I switch to some other themes already installed on my WordPress, PWAL works properly (but not for all themes).
My current theme is Twenty Ten and I have done the most recent update of the theme.
I have just also bought a theme on ThemeForest (The Omega Theme => http://themeforest.net/item/omega-multipurpose-responsive-bootstrap-theme/7660374?s_rank=2), as - obviously, Twenty Ten is a bit old fashioned and I wanted to profit of this plugin issue to have a more modern theme, up to date. But the same problem appears also with the Omega theme.
Thank you for advance. I grant the access to my website of course.