Converted tetraploids can revert back to normal diploids. I do not have much experience with converted tets because of the two that I bought initially one had reverted but the other was still tet. I decided that purchasing 'converted' plants was too much of a gamble.
Converted tetraploids will have fertility problems.
In normal diploids the 22 chromosomes are two sets of 11 chromosomes. We could consider them as being a pair of A chromosomes, a pair of B chromosomes, a pair of C chromosomes, and so on. When it comes time to produce the gametes (the pollen for example) an A chromosome is matched by only one other chromosome, the other A and so the two A chromosomes will align with each other perfectly. Then when the pollen grains are finished being formed each will have exactly one chromosome of each pair. The pollen grains will have 11 chromosomes, exactly half of the normal 22 and they will be one each of the A, B, C, D, E, F, G, H, I, J, and K chromosomes. The ovules will also have 11 chromosomes and one each of 11 pairs. When the two gametes unite the seedling will have 22 chromosomes and exactly two of each of the 11.
In converted diploids (tetraploids) there are four sets of 11 chromosomes. An A chromosome is not matched by only one other A chromosome but by three other A chromosomes. When it comes time for the chromosomes to align themselves there are problems. Instead of one A chromosome aligning with one A chromosome and the remaining two A chromosomes aligning with each other there will sometimes be four A chromosomes aligned in a block or three A chromosomes aligned in a block with one A chromosome left alone. This can happen for each of the 11 chromosome types at random and independently. The end result is that the gametes (pollen and ovules) are not genetically perfect. Only some will have 22 chromosomes, two each of the 11 pairs. The rest will have some number such as 23 or 24 or 21 or 20, and so on. Even those with 22 chromosomes may not be proper, as they may have three A chromosomes and only one B chromosome (and so on) and the sets of three could be matched by sets of one to give a total of 22. The total might be correct as a number but not as a proper balance of two of each of the 11 chromosomes. When the chromosomes are not proper the gametes may not be viable or the seed may not be viable and abort.
Converted tets can be difficult to use because of their lower than normal fertility. Or converted tets can be difficult to use on tets because they are not tetraploid but have reverted back to being diploids.
Another interesting thing is that I have 2 healthy fat seed pods on tet super fancy face X tet Texas kaleidoscope. Sooooooo obviously they are the same ploidy.
Unfortunately, if pods set on known tets are aborting and the pods set on each other do not abort then that suggests that both conversions have reverted to being diploids. Perhaps you could try using both 'conversions' on known diploids, if you grow some. Tetraploid pollen on a diploid will set pods that remain for a week or two usually but can remain longer and rarely can produce a triploid seed. However, most such pods will abort. Diploid pollen set on a diploid should set pods that remain although some can abort (depends on the fertility of the pollen and of the pod parent).
