Contacts .vcf -file cannot be imported into Android Nougat 7.1.1 phone

I have tried two different Android Nougat 7.1.1 ROMs and noticed that the Nextcloud contacts .vcf file exported from Nextcloud cannot be imported into Android. Phone says “vCard format not supported”.

I’ve tried this on NextCloud version 11.0.1, 11.0.2 and also 1.4.2017 daily. I also have latest Contacts app installed on Nextcloud. NC is running on Linux mint 17.3 & Nginx.

Any idea why?