Hyperstudy problem with Flux solver batching

Hi
I have used hyperstudy with flux solver for a while. with the new version, I get into a new problem.
In the DOE, sometimes it will run into an error (attached picture).
When I increase the number of multi execution, the number of failure increase drastically.
I checked the files of the instances that have errors:
1. the flux file was not created at all or 2. the resulted Hstp file is not created.
Before this error, it will give this warning too:
[64612|1642966487198|1|WARNING ][UseCase|UseCaseManager.changeUseCase] : No use case transaction found
[64687|1642966645613|1|WARNING ][ExecuteBatchSpyAction|ExecuteBatchSpyAndExitAction.doAction] : Execution of C:/Program Files/Altair/2021.2/hwdesktop/hst/scripts/python/python3.5/win64/alt/hst/eac/cmd/hstupdate_flux.py failed: Traceback (most recent call last): File "C:/Program Files/Altair/2021.2/hwdesktop/hst/scripts/python/python3.5/win64/alt/hst/eac/cmd/hstupdate_flux.py", line 585, in <module> main() File "C:/Program Files/Altair/2021.2/hwdesktop/hst/scripts/python/python3.5/win64/alt/hst/eac/cmd/hstupdate_flux.py", line 550, in main hstUpdate.updateProject() File "C:/Program Files/Altair/2021.2/hwdesktop/hst/scripts/python/python3.5/win64/alt/hst/eac/cmd/hstupdate_flux.py", line 550, in main hstUpdate.updateProject() File "C:/Program Files/Altair/2021.2/hwdesktop/hst/scripts/python/python3.5/win64/alt/hst/eac/cmd/hstupdate_flux.py", line 453, in updateProject raise ex
Thank you in advance for your kind support.