Dimensions Issue

Something has altered in settings ? somewhere… All of a sudden all of my dimension lines (in layout) are at 15 degrees to the vertical / horizontal…
It’s impossible to get a dimension to sit correctly - which setting is this please ?

If I click on an existing vertical/horizontal dimension the gumball is at 15degrees to to it

It looks like a CPlane issue - but cplane is normal (world - top or world front)
It’s the same for all / any dimension styles
It is only a problem on one layout
It is not a problem when using the standard viewports (i.e. non layout)

I am using section tools btw

If I click on the dimension and then change the gumball option to ‘align to world’ rather than ‘align to Cplane’ then the gumball reverts to the correct alignment.
So it is definitely a CPlane issue. But selecting view /change Cplane/ and setting to world front / world top has no impact/makes no difference (when in the layout screen)

I shut down Rhino. Re-started and in the viewport screen I set view > World Top (again - having done so several times already)
The second time it worked.
I think this may be a bug ?