How to add OVERLAP_BP field to VEP output?
I also opened this as a Github issue, and received the following response:


  It seems there are some inconsistencies on our end. I'm looking into it.
  Until the fix, using --fields OverlapBP,OverlapPC works with any output format, while --fields OVERLAP_BP,OVERLAP_PC works only with default output format.
  
  A small note that this overlap data is available for structural variants only.