So far it seems to work about 5-9 out 10 times. Resuming can have issues with the modem as well, where it just will not come back. Other issues are that the lock screen just loop when unlocking and never unlocks. This instability is seen on the MNT Reform as well. It just feels more frustrating on the Librem 5. Really hoping software development continues to work and these issues get resolved.
One final note: Auto suspend seems to work more often than when you manually trigger standby via the Librem 5 app.