This could be a couple of things. First we cannot rule out a faulty rack. However, I am attaching the instructions on how to replace the rack for your review just to eliminate the possibility that you may have missed something.
Next we need to make sure the system is bleed properly. Just letting it sit to get the bubbles out doesn't purge it enough. I also attached the bleeding process that we need to run through because if it bleeds the air out it may restore the operation. However, if it does not then it is possible that the rack was faulty or has now failed if run with no fluid long enough.
Let's run through this and go from there. Thanks
Images (Click to enlarge)
Wednesday, October 14th, 2020 AT 6:12 PM