Lychee and Caimito seeds

I’ve had some lychee seeds in a paper towel for a while and the little nubs sprouted but I can’t seem to get a taproot to come out of the seeds. Is this normal for lychee seeds and if so how long does it usually take for the taproot to come out?

My second issue is caimito star apple seeds. I’m not sure whether to tell if they’ve “germinated” but the seeds turned from white to green and the roots grew a little. However, I’ve placed some in soil and I’ve had no root growth for multiple days to a week. Is this normal?

If you need me to post a picture I can just let me know