Block textures are not rendered properly, or possibly the camera is not in the same location as the loaded chunks, when using timeline jumps that miss a dimension change or teleport. This causes nothing to be viewable except the skybox and sometimes particle effects. Observed in 1.12.2 on a skyblock server after player has traveled to the server shop, to other player's islands, and to the nether. Observed with both classic and vanillish controls. Observed with both spectating and free-travel modes. Some chunk loading errors observed also when chunks are not unloaded but a timeline jump of greater than 10 minutes is performed.
A possible solution:
Is there some way to snap the camera to the loaded chunks/ player? If the camera is in the wrong position, it would be nice to be able to move to the correct position and see if the blocks load properly. Also this might separate out the "position NaN" bug that has been previously reported.