Is there a way to fix this - or replace the MD3?
It is hard to tell, it could be an unusual bug that comes with a combination of firmware and application.
If you have a 5.x version of the application it could be a good idea to start the MD3 by bypassing the application and trying if that solve the problem. (specifically thinking about one case fixed in 5.01)
It could also be related to hardware, in which case the module should be replaced. Had a similar case some years ago on MDL2: https://forum.iqan.se/communities/1/topics/736-iqan-mdl2
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