We cruise full time and live on the anchor most of the time.
I have had to anchor in 4:1 in tight spaces with strong tidal changes twice a day. Anchored in many 'soft mud' bottoms.
Chain helps, do not go with less.
Trying to set the anchor at 2:1 will increase the chances of pulling it out.
I suspect your problem is that you are trying to set too hard too soon. When we drop in likely soft mud bottoms, we do not throttle up hard in reverse. We put the boat in reverse with no throttle and let the boat back down gently until the chain is fairly tight. Then just a slight bump up of the throttle to around 1000rpm. If conditions are benign, that's all we do. This lets the anchor settle down into the mud. Later, if there is a threat of high wind, we'll turn the engine on and throttle up full in reverse to check if the anchor is holding. Works every time...so far! Just had 7 boats rafted to us in a soft mud Chessy bottom. Wind was under 5 when we set but over a 12 hour period it switched around 360d and picked up to around 15k at times; 4:1 scope and we held fine