OPs can't craft

Since no answers have popped up yet, I would just like to suggest a possible solution in cases like these.

First off, Pocket Edition Minecraft has been updated since the time of this post, so I presume that the Plugins used on the server have also updated since that time.(And most likely, this bug has disappeared form existence)

The problem with not being able to craft was quite obviously caused by either: PocketMine(Very Highly Doubtful, since I never had this problem) or by a Plugin(Highest Possibility). Again, this issue was probably fixed by the time I am writing this.

In all likeliness, the crafting error was caused by a Plugin.(Probably poorly written, or bad perms) What I would do when I came across a Plugin problem, was to disable all plugins, and test the issue occurring plugin by plugin. When the plugin causing the issue is found, the best option would be to go and contact the Plugin Dev, to see if the issue could be resolved. If the issue couldn't be resolved, You would either have to simply live with having to de-op yourself to craft, or disable the plugin.

IMO, topics like this should be locked. It is the server owner's responsibility to edit or remove faulty plugins. When I ran a server, I did all of the maintenance by myself, which did include occasionally contacting devs.