What information is greatly lacking which does not allow us to propose a solid theory for origin of life ?
First of all, we do have some solid theories to explain the origin of life. That said, the main thing missing in order to be able to accept one of these theories with a decent amount of certainty is the ability to run a planetary scale experiment for a few billion years.
The theories are fine, the problem is that we cannot really test them. In order to test a theory that describes the origin of life, we will have to recreate the original conditions (think of a test tube the size of the Earth) and then pump energy into the system and watch what happens over the next few billions of years. This is not really feasible, for obvious reasons. I really doubt you will be able to get funding for an experiment that will run that long.
The reason for no single, solid origin of life (OOL) theory is that there are many and none of them explain or resolve the overall or the detailed issues of OOL, encompassing wide differential and even conflicting approaches, e.g., reproduction vs metabolism, and RNA vs DNA. Further, all are using naturalistic processes, requiring validation by the laws of physics and experimentation. While there are numerous theories, they are either geochemically irrelevant or outside the laws of physics. Whether RNA world, panspermia, hydrothermal vents, small warm ponds, all embrace various levels of chemical evolution for the initial, intermediate and ultimate biochemical assembly of increasingly more complicated levels of organic elements considered vital to OOL. No viable processes have been found to naturalistically create life.
Increasingly, wild speculation of geochemical conditions and trivialization of biochemical assembly, metabolism and reproduction are being proposed. The intractable problems that apply to naturalistic theories begins with the fact that chemical evolution of non-living compounds produces no viable pathway to increased complexity, that is, there are no cosmic evolutionary processes capable of the complex structure, design, order and operation of biochemical systems required for even the simplest organism.
The universal challenges that must be fully resolved in all theories include: 1. The homochirality essential in nucleotide amino acids, 2. The homopolymerization of the DNA side chains, 3. The nucleotide coding using information design, 4. The cell membrane formation essential encapsulation. 5. The chicken and egg issue of proteins and complex structures.
These are affected by requirements for colocation. coincidence, contamination mitigation and concentrations that are absolutely precise.
Finally, lab experiments must accurately reflect geochemically relevant conditions and not overly manipulated by experimenters, which would simulate intelligent design but produce questionable results.
The number of sources that could be listed is extensive. A simple search internet of the main descriptive words would provide detailed definition and additional detail. Regarding the 5 universal challenges: 1. homochirality relates to the right/left handedness of the amino acids since they are not symmetric. DNA amino acids must be 100% left handed or DNA will not work. One of the challenges to get comprehensive sourcing is due to the reluctance of present biological entities to fully acknowledge the delineated intractable issues.