I found that sometimes DQR jobs failed, for example see here (only availabe from DGS network).
The error message is :
RuntimeError: Cannot find all relevant data on any known server. Try again using the verbose=True keyword argument to see detailed failures.
I checked the log and found that the MDC trigger time is earlier than the time the latest frame file was generated. Due to this reason, the NDS on gwpy can't find the frame data and DQR jobs failed.
I chatted with YamaT-san about this issue. One of solutions is to run DQR at upper stream on DGS network called DMT network. We will continue to work on this.