I think Tris-Acetate gels and associated buffers are the right call for high MW proteins. Have you done coomassie brilliant blue staining to your gels before transfer? that way you can see if the electrophoresis is running properly. Maybe transfer is the problem, there are many variables involved. First, wet transfer is a lot better than semi-dry and dry (I takes a lot more time tho). If it is possible, I would suggest you do wet transfer for 2 hours at 70 V in transfer buffer containing 20% methanol. Also lowering the methanol concentration from 20% to 5% and increasing transfer time to 3 hours are helpful for the transfer of proteins over 200 kDa.

If you do not have that possibility, increase transfer time, at least double I would say (you may lose some low MW proteins, but high MW should be better). Also, for high MW targets, gel thickness is an important consideration, the thicker the gel, the longer it will take to transfer. wet transfer yields stronger signal regardless of thickness tho.

I hope this helps.

Yes, I have done Coomassie brilliant blue staining of gel before and after transfer. Some high molecular wt proteins are there after transfer (10 min at 25V bio rad semitransfer). I will try as you have suggested. Thanks for the suggestion. I really appreciate it.