Hi rcseisland,
It would certainly be possible yes. The PLB foundation is not particularly good quality and it could be allowing the mattress to sink into the wider gaps. You can see some comments about their foundation in post #44 here and the posts it links to. You could test the effect of the foundation by either sleeping with your mattress on the floor or by putting a sheet of plywood over the foundation to see if it makes a difference in your experience. If this helps then an adjustable bed would also have a solid non flexing support surface and it would provide the same support as having your mattress on the floor or with a sheet of plywood underneath it.
The Nature has 2" of 21 ILD latex over 2" of 28 ILD latex over a firmer support core which is somewhat similar to the Dreamfoam mattress you tried earlier which had 1.5" of softer quilting foam over a 3" layer of 28 ILD latex and since that was too firm for you and given your lighter weight it’s also possible that the Nature may be a little on the firm side for you as well and if that’s the case then some of the suggestions in post #2 here may be helpful.
There is also more information in post #2 here about the more common symptoms that people may experience on a mattress and some of the possible reasons behind them that may also help you to clarify the types of changes that may help with the “symptoms” you are experiencing.
While there is no way for me to know with any certainty because I can’t feel what you feel on a mattress … if none of these suggestions are helpful and if I had to guess about the types of changes that may make a difference I would say that you may do better with some additional thickness/softness in your comfort layers.
Phoenix