I noticed something for a while, but only recently I figured out how things work.
So if you have some boards at ignore you can't quote posts from them.During times I noticed sometimes that I can't quote some posts but I did not know why. When I was clicking on Quote button the screen made a short refresh but the quoted text did not appear in the Quick-Reply field. After I kept encountering this situation for a long time I finally managed to understand why that was happening.
The problem occurred only when I was trying to quote texts (posts / topics) from ignored boards. However, you can open links of posts from ignored boards.
Let's take this link, for example:
https://bitcointalk.org/index.php?topic=5470785.0. It is from a topic posted in Russian local board, inside Hoвички child board. If you have Russian board at ignore (together with all its child boards) or if you only ignore Hoвички board, the link will still open when you click on it. But you can't quote it.
A similar situation occurs also when trying to merit posts from ignored board: you can't do it. However, when trying to do that, you get an error message, saying that you can not merit that post. But when you try to quote a post from an ignored board no error message is displayed, which makes things more confusing.
I thought to share this with the rest of the users, in case others also encountered this issue and did not know why it happened.