Simple solution! Davinci Resolve Studio 16.3 beta 3 . Playback menu - delete Render cache - all
I struggled for weeks with this media offline but not offline error. I was running 16.1.2 studio and one day after not opening a feature film project for several weeks, it opened up with all media showing online in the media pool, but the player and viewer windows wold only recognize media as offline. I upgraded to 16.3 as Dwaine recommended. Unfortunately, I learned at that upgrade that my dongle was pirated.
I caught the B&H sale and bought a dongle with the free micro controller upgrade last week. Yesterday I was excited to install resolve studio 16.3 b3 again with a real dongle and load up my project. I was sad to see that the same online - but not offline error persisted. This was beginning to remind me of my toddlers tantrums where he would break down crying about some paradox like " I want but I don't want!", so I took a few breaths and looked at the forums again thinking it may be some cache error..
YES! That was it. I went to Playback Menu - Delete Render Cache- All, and Abracadabra! my media was back online and happy. Much easier than relinking 300 some clips by hand
Thank to everyone on this knowledge base for their support in helping me search out a solution!
My late-Jurassic Mac system still chews up 4K Prores: (OXS 10.13.6, Mac Pro 4,1->5,1 96Gb Ram, 12 core 3.333, 12Gb Nvidia Titan XP, BMD Decklink Duo 2 I/O, Caldigit Fasta USB3/SATA 6G card)
“Until you make the unconscious conscious, it will direct your life and you will call it fate.” - C.G. Jung