XBee S2C waking on UART when ENABLE_WAKEUP_FROM_UART is False

I have a couple of new S2C programmable TH modules that I would like to keep sleeping until (only) the timeout period expires. This works flawlessly unless my sleep period is over a couple of minutes. pm_get_wakeup_source indicates the UART as being the culprit even with nothing hooked to DIN or DOUT except for a scope which shows no activity. ENABLE_WAKEUP_FROM_UART is false and I never noticed the issue with shorter sleep periods. When it wakes, the SLEEP_REQUEST pin IS firing low, so perhaps it’s a radio issue (setting). Any assistance would be appreciated to avoid sloppy work-arounds!

XB24C TH HW 2E45 FW 4060 with XBee in pin-hibernate mode.

Thanks in advance!