I just had trouble with this and took me a while to find the answer, so I thought I'd post it in case anyone else was having the same problem.
The problem is that global content blocks don't work in product descriptions in the products module.
The fix is simply go into the detail template, and change {$entry->details} to {eval var=$entry->details}
Hope it helps someone.
Cheers,
Luke
[solved] Global content blocks in "Products" Product Descriptions
Re: [solved] Global content blocks in "Products" Product Descriptions
Excellent and timely tip for me.
Thanks for taking the trouble to post this Luke.
Thanks for taking the trouble to post this Luke.