Some characteristics need a so called times write for putting values. Frome the OSS HomeKit ADK, Section 6.7.2.4 Timed Write Procedures appears to be related to this issue.
As far as I can see is this available via 'tw' in char['perms'] (as returned by list_accessories_and_characteristics.
Note that this is part of the Lock Mechanism Target State I am currently playing around with.