Hi,
I am working on setting up a plan in PAW for a client and I can't show screenshots of my whole setup but hoping I can talk through it here and get some direction to resolve this.
Have created a plan with a task to input SG&A expenses that is linked to a SG&A input book (containing a websheet), this book is under a sub-folder that contains different books for inputting other types of expenses. The book is inheriting permissions from the sub-folder.
The following error is popping up as I try to save the task in the plan: 
Obviously the inheritance is clashing with the task security in some way as if I turn the permission inheritance off, I don't receive the error.
Why are tasks in plans unable to use a book that is inheriting permissions?
We have setup the related expense input books together in the sub-folder to group them for logical navigation and we don't want to manage the permissions for each individual book, hence the permission inheritance.
Thanks,
Ronan