Certificate Authority installation doesn't work

Question

I've seen many many posts* lined to my problem, although none of them seems to refer to my bug. I set up my small PKI (for Web, mail etc.) and now try to import my CA .crt file to my Android device. Each time I try to open the cert file I am prompted for entering a name for the imported CA. I then validate the name and the purpose (VPN and applications) and a small Pop-up appears "MyCA has been imported." However, when I go to Preferences > Security > Trusted certificates > User certificates, my CA doesn't appear.

I tried to download it :

• via Web (URL pointing directly to the .crt file encoded in PEM)
• with the file (uploaded to Downloads/ folder, then Import from SD > Internal, same behavior)
• via ADB to the added-certs/ folder (access restrictions indeed)

Does someone have an idea ?

My phone : Android 5.1.1 OxygenOS 2.1.2 OnePlus X

Thanks !

*Unable to Install Certificate

*How do I install a user certificate?

*http://androidforums.com/threads/cant-install-security-certificate.668968/

*How do you import CA certificates onto an Android phone?