No sound in 12.5

I suddenly lost sound and waveforms in 12.5 in the middle of a project. Never had this before. Tried all the usual checks and reinstalled - no good.
However I imported a clip from a previous project and lo and behold sound and waveforms were there on that clip but still not on the present project. What's going on ?

If your lost sound is AC3 from AVCHD codec, the cause seems to be the last Windows 10 update (1803) which "removed" Resolve support to this audio codec - at least with 14.3 and 15 versions.

Thanks Gerron. Yes it is GH4 AVCHD AC3. And I am on Windows 10 but if that's the problem what to do about it ?

I restored Windows 10 to the last update with on desktop (14.3) and notebook (15 beta3).
AC3 sound came back.
But now I can`t uninstall 14.3 from the desktop (Windows Professional) and install 15.3 because it miss the Resolve installer package. And, I don`t now why, no problem with the notebook (Windows Home) restoring.
Gerron

Sorry my no sound on the timeline is from a GH4 4k in MOV and LPCM. I tried it in Resolve 15 and the sound is there but after 20 mins happily editing I got GPU Full. Possibly due to my Radion HD 7800 card.

I have recovered my lost sound by relinking the clips. So the problem was simpler than I thought. Just hope I don't have to relink again.