All my images, except the first one, are washed out when running LRT.

Very little information, I need to guess.
I would think you messed something up with the gradients/masks.
I'd recommend reading the instructions and doing the workflow according to the instructions again step by step.
To have a clean start, remove the sequence from Lightroom and in LRTimelapse do "Metadata / initialize".

Then start as explained here: https://LRTimelapse.com/workflow

If the problems persist, please provide more information and send the log (info menu/show log).

Hi Gunther, I opted to send you the log file via email. The issue is fixed, and I believe the problem was the gradients.
Thanks for your help,
Hugo