@FiiO
1) Yes resume mode is on, the issue is from Fiio music app only. Poweramp I have a purchased version and suddenly said that you need to verify the purchase so i moved on to Fiio App. Fiio App at MOST (not all) of the times would pick up my 1 particular Led Zep song from entire two micro SDs and worst part is when that happens, it plays just tht song. The forward and back buttons do not work and its like you have shut down the app, clear from background activities and then restart the app again.
2) different sampling rate, all are flac24, some flac 16, and variable sampling
3) This shuffle really bothers me, i know the songs it will pick, so seems like an algorithm built in to only jump certain steps thus same sequence of songs keep coming in.
4) Now my latest mystery. I have 2 micro SD cards - both 128 gb and both almost full. So i try various music apps i downloaded 4-5 of them. All are showing me a different number of tracks in my library of "All songs". The variation is not small.
Onkyo Player shows 2845 Songs
Poweramp - 3672 songs
Neutron Player - 4001 Songs
Fiio App - 3736 Songs
Aimp- 3593 Songs
Variation is from 2845 to 4001 thats a huge difference. And all players support most of the music formats too.
@superuser1 - withdrawal symptoms were there