It's not just you. When SmartThings works as intended, it's absolutely my favorite home automation system, but it is just not reliable enough for many of my use cases and I've had to move a lot of devices off of it. I'm quadriparetic, so I have to pay someone else even to change the batteries in a device. I realized that because of the amount of maintenance required, SmartThings was costing me about $50 a week. It wasn't a huge amount of work, but it was a lot of constant fiddling just to keep things working that had already been working.
The company is very aware of the issues and they have committed to improving reliability and stability. The CEO posted to these forums a couple of months ago:
They also made a major corporate commitment about a month after that and hired Robert Parker, who was a director of engineering at Amazon, as their new head of engineering.
For myself, since last November I have yet to go 10 days without an impactful SmartThings failure. The exact error varies, as well as the devices involved. It's just an ongoing situation.
I certainly hope that they achieve a stable environment. From an engineering standpoint, I'd give Parker a year to turn things around, but I would guess realistically that Samsung will set a shorter timeline than that. But it needs to have more predictability before they can release it as a feature on Samsung televisions. So I'm sure there are a lot of people looking into this.
If you're interested, the following has my own experiences, but you can just search the forum for stability or reliability and you will find much discussion.