I'm David from the WPML Dev Team. I am here to help you fixing this issue and hope we can fix it asap.
Is weird that code works on some products but not in others. However, makes more sense if it doesn't work than working. No matter the reason (at least for now), let's find a way to fix.
After a deep dubugging journal I found that we probably do not need to run a SQL command to fix this. For now, as a first step (hope is the last one) let's start by adding the code you'll find here on this gist hidden link where you find more convenient (it can be your theme functions.php file).
Since I don't have ftp access I can't add this code. I do highly recommend using ftp to edit the file (however you can also do it from the WP Editor File).
Please let me know if you need help on running the site.
If you want, you can create a backup before adding the code, but anyway, the code doesn't modify database. Please keep me posted.
Hi David, thank you for your patience, it works, now i am able to generate a gmc feed via wpallexport where the price is converted so this is a huge win.
I am happy to hear that works perfect! It's been a pleasure for me to help you solving this. Please let me know if you need something else associated to this.