1) Are you using shielding gas? The otoflash can't cure under vacuum, if you forget the gas with resins that need it (or use the wrong gas setting) the results are almost always unusable, you don't have any room to deviate from the manufacturer's specified settings.
2) The otoflash's single exposure side- and flash tubes that don't quiite fully cover the full inner surface of the tray's usable area- means it's particularly susceptible to uneven curing or 'shadowing', especially in deep pockets with sheet sides. Where a good, even cure is critical, I flip the parts several times instead of the usual 50/50, trying to 'rock' the part so it lies in a different plane than it did the first time you cured that side. That way, if a quirk of geometry and alignment means a tucked-away bit of the part doesn't catch enough rays with one particular angle, it will almost certainly get it with the second.
Even curing inside cavities is always a bear, I actually designed a Curing Lance for non-dental parts that uses a teeny-tiny UV LED set in the tip of a large-gauge hypodermic needle tip so you can properly cure the interior of a hollowed-out part, so long as there's a 3.5mm or wider hole in the part for access. You put the lance through the hole and turn it on, rotating it once or twice to get even coverage inside. You can even supply shielding gas through the needle- in principle anyways, I never had to go that far.
