The keypads have the worst range out of all the alarm devices. Mine consistently lose signal when my motion and door sensors (that are much farther away and in more shielded locations) don’t have an issue. There’s no reason a battery powered sensor should have better connectivity.
Can you create a keypad that can connect to sidewalk or wifi directly? (Rather than having to rely only on z-wave. The z-wave controller/antenna/protocol stack in the keypad seems to be sub-par.)