Hi Kristian, possibly, it depends on what is stopping the tile from being rendered. I would recommend this, please submit a support ticket at https://www.crowd-render.com/report-a-problem. There you can upload a copy of your blend file and also the log files of the addon which will help us diagnose what's gone wrong.

This problem can occur when blender has issued an error during the render, which causes the rendering of a tile (or all tiles if it is a persistent error) to return a blank or black image. Fixing those errors results in the tiles being rendered properly. Sometimes it can be an out of memory error with your scene being too large to fit into the GPU's VRAM, but there are other causes besides this.

So, if you'd like us to help you (and we definitely would like to help you!) please consider submitting the ticket with;

1. Your project files

2. The crowdrender addon log files from both the client and the node that did not render (if all nodes did the same thing, then we can probably just get away with logs from one of the render nodes rather than all of them!). Logs can be automatically packed for you from a button in the crowdrender addon, go to Blender -> user preferences -> addons tab -> Crowdrender -> click the black arrow to expand and scroll down to find "Zip Logs". Do this for the client and the troublesome render nodes.

3. During the render, you might want to check the little info bubble icon next to the node in your crowdrender panel. Useful information can be sent here from the node whilst it is trying to render. It often gives clues as to any errors that stop a render from fully completing.

Looking forward to your ticket ;)

James