For anybody experiencing a similar issue:
The problem with the module in question (SARA-R510M8S HW rev. 00B) has been acknowledged by u-blox and they will have it resolved in their next hardware revision 01B.
Unfortunately, there will be no fix beyond Mario’s workaround from u-blox for hw revision 00B.
Thx to Mario for the thorough analysis and help in getting this issue resolved.