Erroneous "question put on hold since you loaded page" prevents flagging

Question

On this question:

1. I visited the question.
2. I closed it as a dupe.
3. I attempted to also flag it with a merge request.
4. I was met with an error saying that the question was put on hold since I loaded the page, which is strange because I've gone through the close → immediate flag sequence many, many times in the past with no issue.
5. I reloaded the page.
6. I continued to be met with the same error, which seems broken since I've reloaded the page since it was put on hold.

Here is a video showing reload → flag attempt (yellow circle indicates mouse click):

Browser is Chrome 52.0.2743.116 on Windows 7.

PS: I re-opened that question because I realized it was subtly different. Just... don't worry about that.