Hello,
The issue was rectified in later versions of Firmware which were released after 2.3.2.
Please test on latest firmware.
Download the latest Firmware from https://source.sierrawireless.com/resources/airprime/software/hl6528rdx-firmware-2,-d-,3,-d-,10/
You can check is module is in sleep mode or not by checking power consumption 1.2 mA
Thanks & Regards,
Moderator