Peco Insulfrog Nscale Turnout Short?

[Steamtrains]

I think your problem is with the width of the wheels themselves, If too wide,, they can bridge the gaps between both rails at the frog. Solution..? Check around to see which wheels are the narrowest and replace, or cut a gap beyond the frog....

I had a similar problem with a tender's wheels bridging the gap at the points on the diverging route...