What way are you starting the game? From the shortcut or from origin menu? Idk why, but I've had issues with it starting from the shortcut sometimes. Never did look into it, so maybe was just some weirdness with mods or something in my case, but if you are doing it from the shortcut, maybe try from origin menu (e.g. go to it in the game library and launch from there) just in case.
All I can think of atm if you've already tried repair, taking out mods, etc.
Edit: Also, you could see if the fail to launch is producing a lastCrash file in sims 4 folder (the same one where lastExceptions show up). I don't think anyone other than EA has the info to interpret lastCrash files, but it would at least point to whether the game is crashing for some reason, or just failing to start.
