Advice Request: regarding Covenant and bugs with it's settlement system

This playthrough I decided to side with the mayor and the scientist lady, and killed Honest Dan. As we all know, Covenant is buggy as fuck. After gaining access to the workshop, I realized that I couldn't assign most of the settlers to anything, causing the happiness of the settlement to drop significantly. Furthermore, the mayor kept trying to give me a settlement quest involving raiders or some shit, but every time I'd speak to him he wouldn't have any voiced dialouge, and the conversation would freeze up unless I walked away and came back.

I decided to kill every settler that wouldn't take commands or assignments. Roleplay wise, I decided that my character learned that secrets involving the SAFE test were still being kept from me by town leadership. One by one, I picked them all off with Chao's Revenge, making sure to stay out of the sight of the turrets and other settlers. Most of the kills were satisfying, but I couldn't help but feel guilty about murdering Talia. Chances are she was too naive to realize what she was involved in, but she still had to pay the price for her betrayal.

After the cleansing, the only remaining settlers are the two unnamed ones, Ted, and the Doctor. They all can be assigned to things. Unfortunately, however, the happiness of the settlement does not seem to be rising. I've built workshop items to increase happiness and made sure to meet all requirements for food, water, beds, and defense.

Can anyone shed some insight as to how I can fix this problem? Disclaimer: I play on PS4 and don't use mods other than CC. Is Covenant just too fucked to be reliable as a settlement, period? Or would killing the remaining settlers and starting fresh perhaps fix the issue? Ideally I just want to set up a mini market to get some caps rolling in, but I don't want to have to constantly worry about settlement happiness dropping to dangerous levels.

Thanks all. Sorry for the wall of text.