Text in type on path is distorted on export to png

[defaultvspfxly2mzsi]

All text and graphics look fine in ai but on export to create a png the text which has been typed on a path is distorted or the wrong size. I am not aware of changing any settings but the previous day I had been experementing with the new features in 3D and materials, in doing so and whilst using text I downloaded a materials file from the community settings.

Any ideas please?

[Met1]

Not sure why you would get a filter effect on export but you might want to reset prefs although I have no idea how that's affecting things.

Failing that does it work ok when using outline text?

[defaultvspfxly2mzsi]

It weird. I took and old doc and on export everything was fine. I then changed the text font and the problem resurfaced. I ended up just expanding the text to create an object and then all exports were ok.

Thanks.