J-Flash/J-Link V6.50a works perfectly. There's a bug in V7.45c, which I have reported to Segger.
Update Jan 20, 2022 from Segger:
Upcoming release of Segger J-Link/J-Flash will include fix for this issue.
The issue was due to a speed optimization that relied on the availability of an external reference clock, RTCK, which is not the case with many devices, including the NXP K8x.
Update Jan 25, 2022:
Segger J-Link/J-Flash V7.60f available for download. Fix for K8x issue included in this release.