No. Have a look here for possible reasons/solutions:
Try to make a factory reset first. (Go in settings to backup & restore). Note that this will delete all data, yet I am suggesting this since you said your phone is new.
It is possible that when installing Open OS the length of a partition got messed up and the phone can’t write the encryption header (This depends on the way how you installed the OS; see for example here). A factory reset should solve this issue. Try to encrypt again right after the factory reset.