I wanted to chime in here to clarify a few things.
About a month or so, when we first saw this behaviour, we were able to pin it down to a small issue in the activation process that has since been ironed out. That is why refreshing these on the network solved most issues.
At this stage if you are running into similar issues we recommend you first confirm that your APN is set to ‘hologram’ failure to do so on most modems means that you will not get access to data.
If your APN is ‘hologram’ and you are still having issue connecting for the first time we recommend testing your SIM out on an unlocked mobile phone. In the past we have seen firmware that causes the modem time out before the SIM has enough time to preform its first network registration (which takes significantly more than subsequent times).
I would also recommend checking out this video we made on connecting 3rd party hardware: https://www.youtube.com/watch?v=jYi8BJgU6tI&t=65s.