Cubase 10 win 10 no sound sometimes?

When I open a project, half the times no sound comes out. Midi signal is going through, but no stereo out. I’ve tried checking f4 and studio setup, but the only thing that fixes this is when I close cubase and start again(and that sometimes that doesn’t work, so I have to close and reopen until it works).
Does anyone have this problem?

Hi,

Can you see the signal on the Channel meters? Are these Instrument tracks or MIDI Tracks routed to the Rack Instrument?