Gotcha, I tried that but it didn't go away, but I fixed it by adding ".value" to the end, like {{ product.metafields.custom.size.value }}

Was the metafield named "size"? I think I got into the same situation and mine was named "size" - I think that caused an issue as that is also a liquid property.https://shopify.github.io/liquid/filters/size/

I now use the flag --theme-editor-sync all the time when running dev.

Seriously, has this happened to nobody? I think what happens is that it times out from inactivity, then restarts theme dev. I was making a ton of edits in the theme customizer, and this OVERWRITES IT ALL. This is a problem. It should at least not aut...

Sometimes while running shopify theme dev I'll see in the terminal, "Stopping..." Then in will relaunch, pushing my files up again, and undoing any changes I had done, but not pulled yet, from the Theme Customizer.  Any solution to this? It's doing t...

This happened to me twice today - once after getting logged out, then again after the power went out.I realized what I should've done: run "shopify theme pull" and select my dev theme, then run "shopify theme serve"