I have already mentioned the problem in another reply above.
People try mostly the fusion between hydrogen isotopes, or at most between hydrogen and lithium, because these nuclei have a low electric charge, 1 for hydrogen and 3 for lithium, so that the repulsion forces between them are relatively small.
When nuclei with greater electric charge are involved, e.g. boron, the repulsion forces increase. To overcome them, the nuclei must have a higher relative velocity before collision.
There are 2 ways to obtain high-speed nuclei, either by heating some plasma until the nuclei have a random thermal motion with high-enough typical velocities, or instead of heating everything and hoping for random collisions, you accelerate somehow some nuclei towards others, so that their movement is directed, not random.
It is already very difficult to contain plasma hot enough for deuterium fusion. There are very small chances for being able to contain and control the much hotter plasma that would be needed for fusion reactions with heavier nuclei.
So attempting to do hydrogen-boron fusion with the methods tried for deuterium-tritium seems doomed to fail.
The workaround is to abandon the thermal way and to search for a way to cause the fusion of accelerated nuclei, using some combination of electric fields, magnetic fields and lasers.
To produce more energy than consumed, it is required to have a very high probability that the accelerated nuclei will collide with their target (which might be fixed or also accelerated). For this either the ion beams would have to be very dense, or their positions would have to be controlled with nanometer precision or a single primary collision should cause multiple secondary collisions, or some other means would have to be discovered to ensure that the accelerated ions collide with the target instead of missing it.
All of the methods that have been imagined yet have a collision probability lower than needed by a few orders of magnitude.
So several real breakthroughs would be needed to be able to produce energy in this way.
The only hope for this is based on the fact that are no known reasons that would make this target impossible, while for the deuterium based fusion reactions there are a few serious disadvantages that are impossible to overcome, mainly caused by the facts that the energy is produced as neutrons and that deuterium and tritium have low availability.