FE599 Intermittent Communication

I have a Schlage FE599 Z-wave lock (on Ring’s certified list). Paired with the Ring alarm system with no issues. However, locking and unlicking from the Ring app is intermittent. The lock is about 12’ from the base station, but in-line with the wall. That means to me that the Z-wave signal has to penetrate several wall studs and that may be weakening the signal. Based on that theory, I placed a range extender in a location that gives it line-of-sight communication to both the base station and the lock. Still intermittent. This is the second Schlage FE599 I tried. The first had the same issue. Any ideas?