v90 not coming back from suspend mode

Hello, i bought recently an v90 and i'm loving it, just one thing i don't get it, if i suspend it (i'm using miyoo Custom firmware) and i come back in 5~10 minutes i can press start and it come back no problem, if i let it in suspend mode more time than this it doesn't come back by pressing the buttons i'm forced to turn it off and when i turn it on again, it turns on normally without showing any warnings at all, anyone know why this happens?