After installing the trial of 2018 I have lost thumbnail preview of all Corel files. I tried setting default application back to 2017, but that didn't help.
Any suggestions?
-B
I had to fix this too and this method worked for me: Right-click on any CDR file and choose Properties from the Context menu. In the Properties dialog, to the right of where it says Opens with... click Change. Choose CorDRAW 2018 from the list of programs and then click OK. You will probably need to do this for Photo-Paint (CPT) files as well, choosing Photo-Paint 2018 as the default.