Had the same issue, and was afraid all my hard work would be lost but I think I found a way to fix it for now!
The conduit issue is new only with 19w12a, so if you go on the launcher to "Launch Options" you can add a new launch option on the last snapshot (19w11b) and play that way. It'll say there might be corruptions going back to an old snapshot, but since you can't get past 1 second into the new snapshot I haven't noticed any issues so far, create a new backup just to be safe. Once in you can get rid of all the activated conduits and play in peace!
Raven Mermuys
Had the same issue, and was afraid all my hard work would be lost but I think I found a way to fix it for now!
The conduit issue is new only with 19w12a, so if you go on the launcher to "Launch Options" you can add a new launch option on the last snapshot (19w11b) and play that way. It'll say there might be corruptions going back to an old snapshot, but since you can't get past 1 second into the new snapshot I haven't noticed any issues so far, create a new backup just to be safe. Once in you can get rid of all the activated conduits and play in peace!