Phew after an extremely lengthy investigation I have been able to
identify that this is direclty related to the fact I had a custom
taxonomy called “year”. Year is already used by wordpress in the
permalinks and this was causing all the problems.I have now had to rename my custom taxonomy. So it is no longer year.
- I found a solution after a bit of searching around.
- This answer should be credited to wordpress.org member nicole2292