Bad Position optical flow

Why optical flow shows bad position while I’m flying on concrete floor also in bright sun light, and there no obstruction In front of flow lens.
I’m using HereFlow ( HEX )
Here’s the screenshot and log;
https://drive.google.com/file/d/1ts2TOGk_7vdmvfg6WuCYuSRrtDdYzU28/view?usp=drivesdk

log8 1-1-1980 5-30-00 AM.bin (988 KB)