Basically what happens is, when the plugin is enabled, (btw i purchased it on Lone, not here) and you reload the server. Whether players have the skills maxed out (the crafting speed one) or not, whenever they try to craft something, it remains stuck on 0 seconds and it won't finish the crafting. They are also not able to cancel the crafting process.
For example C4 Crafting, without the crafting speed skill, it takes 30 seconds to craft a C4 at a Lvl 3 workbench. with crafting speed skill maxed out, it should be 50% faster, so 15 seconds. in both situations the crafting process starts at 0 seconds and it remains on 0 seconds in a constant loop without actually crafting the items. (this counts for every item in the game, no matter what you try), it even doesn't allow you to cancel the crafting. Reconnecting to the server doesn't fix it. it cancels the crafting. But you'll get stuck on 0 seconds crafting again when you try to re-craft something.
I personally had to disable the plugin to make it work again for all my players. So it is definitely plugin related.
I hope to have you informed.