This error may be seen in the bts_log.txt file in the examples/board_test_system folder of the Intel® Stratix® 10 TX Signal Integrity Development Kit Installer Package when the connection of the Board Test System (BTS) / Clock Controller / Power Monitor GUI fails but you can still auto-detect both the system MAX V and Intel® Stratix® 10 TX in the Intel® Quartus® Prime Programmer.
You can confirm if this error is caused by abnormal behavior of the system MAX V (U8) by using the command get_service_paths master in System Console and checking that this does not return the master information.
To fix this error, reprogram U8 with max5.pof which can be found in the examples/max5 folder of the Intel® Stratix® 10 TX Signal Integrity Development Kit Installer Package.