Loss of energy balance information in SIM?

[TPGriffin76]

In the last few days I have revisisted a couple models that I created (in SIM) a few months back. Each seems "intact" (nobody has used them in the interim), but when I recalculate the ouputs, all the energy values have been (wrongly) "zeroed" - all the summary MCal values are identically 0.0.

What has happened here?? I don't know how to recover this functionality, and I do not (if at all possible!) want to recreate these models from scratch. Is there an easy fix, or some required reactivation of the energy calculation functionality?

I am at a loss as to what could have happened, or how to proceed from here. Thank you for any feedback or guidance to solve this issue.
Tom Griffin