WIth great contemplation and effort, I have read your post and pronounce the following:
What…?
??
Can you narrow down what you are referring to? The hotfix fixes some critical things (the custom fields was a good one) but your problem may be related to something else.
When we click on the button “Add Custom Field”, this one disepears if there is no custom and it goes to the custom fields list if some one is already created.