Hopefully one of the guys well versed with MDS will chime in. If the engine had MDS lifters installed I am not sure how they operate without the solenoids. I am not sure of the strategy there. Have you pulled the valve covers to take a look at rockers and such? Another idea could be the rockers were installed incorrectly the shafts have to be orientated properly for the lifters to oil correctly.
I haven't pulled the VC yet. That is quite a project already in the car. I am continuing to research and have found that there are sometimes issues with the lifters taking a long time to "pump up". Something to do with the lifters getting oil from the top rather than through an oil galley. I want to make sure of all the options before I open up the engine prematurely. The valve train was a specific discussion the engine builder and I had prior to building.
