According to the change log, the attachment bug (won't work if comments are disabled) will be fixed in the 5.1 update.
Oogiem said:
New bug. If you quote a post and make a reply. Then want to quote a different post to make another reply even when you click on quote under the new post what gets filled in the bottom reply box is the first one you selected.
I've found a solution for that one on the vBulletin forum (although it still feels like odd behavior): Click the quote button once, it will add the quote to the reply box. Click it again in another post, and you will see in the "floaty bar" at the top that the "Post Reply" button is highlighted and has the number of quotes next to it. Press this button when you have finished quoting, and all the quotes will go into the reply box.
Oogiem said:
Another bug still in existence - Trying to edit a reply during creation the cursor is often placed where you want the edit but the actual text you type goes somewhere else, the end, sometime the beginning, sometimes you cannot select text to change at all Happens a lot to me esp. when I try to fix typos.
​I've seen that one too, but I haven't figured out what triggers it yet.
Oogiem said:
And a third: Is there any resolution on getting the option back to see posts in reverse order in threads? Not the click on the little blue triangles but the old standard revers display? PLEASE! It's painfully slow to use the new way to get to the bottom and is backwards from what I've learned to read so I am finding myself totally confused over and over again.
That feature appears to be well and truly gone - it's missing from vBulletin's own forum too. BUT just above the post, click the Latest Activity button. I may be wrong, but it looks like it shows the first post then your preferred newest first from there on. It's an extra click, but might be less painful for you.