Help with problem saving song (not all parts saving)

[Legendgary]

I've had this keyboard for a long time making hip hop beats and the like and occasionally run into this problem which is extremely upsetting. Sometimes after making a song with about 8 tracks I go to save it and then immediately try to listen to it on the load song menu. Then I notice that' it's only playing about 2-3 of the 8 tracks I made (usually the synths and instruments which I usually keep on tracks 1-8) and not playing any of drum tracks I made which are usually 9-16. I dont know what's wrong as I haven't received an error for this issue and cannot find a solution. Please help me.