I don’t want to say that it’s “common” but it does happen from time to time. Disney IT is shakey at best and the DVC side of thing is exceptionally bad. I was part way thru modifying this morning and got 7 dwarfs. Later, on two of my 4 memberships would load if I accessed the “plan a vacation” link, but my dashboard would not load at all. I finally got all of it to load and was able to modify but it was about 8:20 when it all came together. You’re better off dealing with MS at this point if you have the time to wait on hold.
I don’t know, they keep making improvements in what we can do online. It is frustrating when you’re trying to get in at 8am and then end up tied to the computer though.