I have found that patience is a definite virtue with tropical seeds, especially those from Africa. Many tropical seeds have very limited lives and if they do not germinate soon, they do not germinate. I am finding some African seeds only germinating after very long times. I have some Thaumatococcus danielii just starting to germinate now after about 1 1/2 yrs. Gnetum africanum took 1 to 1 1/4 yrs (& only about 15% germination at that point). I also had some Afromomum just starting after over 1 yr. Not sure why it took so long, what finally prompted them to germinate, or how long they would ultimately be viable. The bottom line is, if they don't rot, don't throw them out. I also had some Jollydora sp that started to germinate within a couple of months, get planted in soil, & not show any signs of growth (above soil) for about 9 months or so.
The seeds referenced above have been kept in damp sphagnum.
John