6x7 Negatives With Better Scanning Holder

Before you suggest it, yes I have attempted to contact Better Scanning. No response to email.
So here's my dilemma. When I use the Better Scanning holder with an Epson 4490 and Epson Scan software with 6x7 negatives it wants to make every scan 6x4.5 I go back to the standard Epson holder and no problem with size.
I've considered cutting the ANR glass to fit the Epson channel and go from there, but before I get that drastic I wondered if anyone here could advise on what may be going wrong.
Thank you.

The scanner read little holes at the top of the scanner that define the film holder and film being scanned. If those get blocked, then that might cause problems.

Make sure the film isn't blocking the holes.

The holes aren't there on the Better Scanning holder. I'll try again to ask the manufacturer.

I looked at BetterScanning site and see a fixed height holder that has been discontinued and a variable height version as the current one available. You did not state which holder you have and it may not matter.
Put your Epson holder and BetterScanning holder together as if they were one holder positioned as they will be when on the scanner for scanning, any physical differences in any of their dimensions?
Somewhere in the settings of EpsonScan Pro screen is a pesky check box for auto marquee, deselect it and manually set the marquee to the frame. I have had problems with the auto marquee clipping usable image area in the past.
There is also the image frame selection on one of the tabs available via the Configuration box at the bottom of the Pro window, ensure the correct size is selected.
My scanners are not currently connected to the computer and I'm working from memory. I have a V500 and a V700.