This appears to be a Venu2 software issue since the Venu1 does not have this issue.
During a CIQ activity without GPS, the FitContributor data stops recording when the display disables and turns off.
The only workaround is to Go to watch main menu> > System> Display > During Activity> set Timeout to Always ON
This issue was tested on 5.38 and 8.05 beta.