Just following up to see if the Zortax team have any more suggestions, at the moment our printer is unusable and costing us money in external print fees.
I am sorry to hear the problem has not been solved. Please, contact us via support form so one of our support agents can provide further help. Also, please attach some videos as the file you uploaded cannot be displayed. Also, please check the extruder’s motion, as shown in step 3. Still - it is rather unlikely that the software/firmware is causing the issues, especially that you already upgraded from 2.4.2 to 2.4.3 and the problem persists.