Printing with external PETG

I ended up in a quite interesting situation with a Zortrax M300 Dual 3D printer.

I had various issues with it and by now, I can print with single material: we bought external PETG, when Ultrat was sold out. Also, we have Premium supporting material, which is compatible with PETG and not with Ultrat.
I tried to print with this as Z-PETG, which work occasionally, but the nozzle got very messy, the material sometimes stuck around it. So, I switched to external material and used the temperature recommended on the label and I have much better results.

After a successful test with single material, I tried the same simple part with dual material.


The printing with dual material started with supporting material, which was fine, sticked to the plate and had the expected pattern. However, once the printer changed to the PETG material, it did not print anything, it was no material movement.
Then I printed it with single material, which was fine.

I get a warning saying something like ‘The file has been prepared for a different type of material’, but it is external PETG, which works alone as single material, and the supporting material is Premium, as this is the original came with the printer and labelled and also that works fine anyway.

Is there a known issue using external material with Zortex supporting material? Thanks.