@Bassie78
Did you try this?
– Open knxproj with 7-zip or simply append .zip and open it in Explorer
– Identify project ID in the format P-XXXX (e.g. P-0413)
– Create an empty file with the name P-XXXX_M-dummy (without extension, e.g. P-0413_M-dummy)
– Copy file into the ZIP file
– Save and remove the zip extension
– Import in ETS 6.0.6 (not 6.1)
sinn3r