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No. The hybrid models don't have the same degradation issues as the Energi. Ford unfortunately had poor programming on the Energi models in regards to the thermal protection and when EV use is allowed, allowing owners who just drive it like any other ICE vehicle to add extra wear to the battery. By the nature of how the hybrid models operate, they don't ever get stressed to the same level and can be driven normally without any extra precautions. The batteries should last the life of the vehicle. As for transmission issues, that's a whole confusing mess. Some owners who have been around the C-Max community for a while have recently started considering that the whole transmission failure concern is a bit overblown. That's not to say it can't happen, but it's been so heavily pushed as a major detractor for the early model years even from those who have not experienced it themselves and just parroting the same line (of which I have been one but I've dialed that back a bit). Also there have been some owners of newer model years including 2017 models that have had their transmissions start to exhibit the same failure symptoms so I wouldn't even count those out of the woods yet. On top of that, no one has really been able to narrow down what the true failure causes are. We all know it comes down to an incorrectly installed bearing installed from the factory that holds the transfer gear and can cause it to slip and eat into the transmission case but its unsure what triggers that to happen in the first place. I've made this recommendation elsewhere and gotten heavily criticized for it, but this is a hill I'll die on: I'd honestly recommend to shorten the transmission fluid change intervals on any C-Max vehicles regardless of if it is a hybrid or Energi or whatever model year it is. Ford's recommendation is 150k miles. I'd probably consider 50-75k but that's just pulling numbers out of my ass if I'm being honest. But the premise being to watch what the fluid comes out like and if there's any sign of wear particles that could indicate the start of a failure. eCVTs by their nature don't have any wear components to them so on a healthy unit there shouldn't ever be any metal particles in the fluid. Changing early can give you a bit of a heads up before a more catastrophic failure. Fluid changes on these aren't difficult or expensive so IMHO it's worth doing so more often for peace of mind. If a potential failure can be caught early, the transmission can be pulled and opened up and get the transfer gear/bearing replaced at a fraction of the cost of replacing the entire transmission.

The ICE running or not makes no difference to voltage. As long as the car is on/in 'Ready to Drive' mode, the DC-DC converter is fully active. Full running should be 14+V. There's also a secondary mode not many are aware of (I only found out after digging deep into the workshop manuals) that when the car is 'awake' by opening the door, unlocking, etc. without actually starting, the DC-DC converter does come online in a kind of baseline/failsafe mode (essentially no input from the vehicle what the desired charging voltage is) that puts out around 13v or so.

From the effects that you are getting, IMO, it sounds as if your 12v battery is failing or borderline. A voltage drop even while driving will spark the SSN message & may go away when battery recovers. When voltage drops, stored codes are being erased. If you can hook-up a voltmeter, I believe you should get 13.5+ volts ICE on or in ACC mode. ICE & ACC mode off, 11+ volts. [please others with more knowledge chime in with better volt numbers]. You can check for a voltage drop when you put on breaks & hopefully it is a brake light short causing problems. Again this is just IMO, no sure fix. Hope this helps. Thanks for the read.