I am a bit curious about this one as well.
I run 2 servers using this plugin, and started to notice issues with bandit and outpost vendors not restocking. I disabled compound-options to see if it was the culprit and the behavior remained, as it does modify vendors and hasnt been touched in a year. Next I disabled vending manager and noticed the problem was resolved. Finally I disabled vending manager once again and re enabled compound options and things remained normal.
Loading vending manager I get:
VendingManager was compiled successfully in 1543ms
Unable to find main plugin class: VendingManager
No previous version to rollback plugin: VendingManager
Full server reboots were done after any changes.
I hope some of that info helps! Thanks again for a great mod.