dstaver, I have the same problem, but I work around it without switching formats. By using the frame offset feature, it is quite manageable to scan any 35mm frame in a strip with the glass holder.
However, I have other big problems. Regularly, when trying to scan the 5th and 6th frames, Silverfast puts the scanner in such a condition that it starts to emit a very very loud noise and vibrate a lot. Very frightening. The process usually freezes at that stage and I have to switch the scanner off and kill Silverfast.
I also have the problem of soft banding with all the holders.
I suspect the culprit of all that to be firmware 1.6 to which Silverfast never really adapted or did not get the relevant information from Microtek.
v**s**n has the same problems, only worse because it does not recongnizes the glass holder at all. But that points to the firmware being the culprit, because it is very unlikely that Silverfast programmers and Ed Hamrick made the same mistakes at the same time.
All in all, it renders Silverfast and the Microtek largely useless for me. I keep using because I have nothing else and sometimes I get sharp scans without knowing why
I am considering to totally give up, bite the bullet and change for another scanner. But which one ? The Nikon and its ill-conceived MF film holders ? Not a bright prospect. An Imacon or a Creo ? Can't swallow the price tag. So, what to do ?