App Connect + Pipedrive: calls log fine, SMS never logs (no error)

RingCentral App Connect with Pipedrive as the CRM. Outbound CALLS log to the Pipedrive deal correctly with full detail. Outbound SMS never logs at all — no error message, the message just never appears as an activity on the Pipedrive Person or the Deal.

What I've already verified:
- "Log SMS conversations automatically" is ON
- "Log phone calls automatically" is ON (and calls do log)
- Multi-contact match behavior is set to "Prompt to select"
- Contact phone numbers are normalized to E.164 (+1XXXXXXXXXX)
- Re-authorized the Pipedrive connection
- Texts are sent from within App Connect (not the standalone app)

Since calls log fine, the connection, auth, and write path clearly work — only SMS fails to log. What would cause SMS specifically to silently not log when calls work?

Also: what version of App Connect should I be on, and is there a known SMS-logging issue in recent versions?