Hi Dave
there are some special options needed on the IB to make the digital crane work.

To operate the 46715 crane the following Intellibox Special Options must be set:
SO 902 = 16
SO 914 = 40
Furthermore the loco address that your crane uses (default is 77) must be set on the Intellibox to use the Motorola New format.
http://debale.home.comca...net/bw/manual.htm#mcrane

This has nothing to do with mfx, the mobile crane does not have an mfx decoder even.
Certainly there is no growing incompatability between the IB and mFx. The IB has never supported an mFx protocol. Some manufacturers do try to introduce such incompatabilities but since the IB supports both Motorola and DCC, any device using those (inclusing mFx decoders) should work.

My 36880 was fully operational with CU6021.
With IB and MS it was moving forward only - reversing was not possible.
With a Delta Control it didn't move at all.

I returned it to M* - they wrote back "We cleaned it" and everything works fine now.
I suspect they did more than just cleaning...
Recently there were several complaints about the quality control at M*.

The IB only knows MM, not mfx - haven't heard of real compatiblity issues.

If a M* item works with all M* control equipment, but fails with the Intellibox then this surely is no problem for M*.
But does such an item exist?

The digital crane has no mfx - it just has a cheapo MM decoder and you may have to fiddle some special options of the Intellibox to make it work. So this is no problem for anybody.

My SVT 137 (#37772 with SDS) works fine with my Intellibox - and so do all my mfx locos. mfx decoders are manufactured by ESU and I don't expect any compatibility issues with mfx decoders.

I mentioned my #36880 - it worked with CU6021, but failed with MS, IB, and Delta Control.
This could lead to problems - e.g. if you habe a CU6021 and sell such a loco to a person with a MS (the buyer will report a problem you cannot replicate).
Or if you have a MS and return the loco to a dealer who tests it with his CU6021 - s/he cannot replicate the problem.

So there is no general compatibility problem with the IB. I'm confident that for locos misbehaving with an IB you'll also find M* control equipment where the loco misbehaves.

If a loco works on one layout with a CS and fails on another layout with an IB, the problem can still be outside the IB. For example I had switched red and brown wires in the track connection - most decoders worked reliably, but few decoders sometimes failed to respond (especially at high speeds). I had to correct the track connections when I finally bought a decoder without automatic polarity detection.
And I had a forgotten 74046 on my layout that caused problems with some decoders while others worked perfectly.