I agree with the objection to the English. I think your suggestion -blocked- could be accepted. I note that -ignored / not followed up- would use different wording in Swedish. Unfortunately -blocked- goes straight into Swedish as -blockerat- , but my dictionary indicates that -blocked- can be translated as -stoppat-. However -förslag- can also be -proposal- and -the proposal was stopped- seems to be OK to me.
In practice the difference is so small that you don't really have to care about it. – When talking about getting hit by cars, it's usually expressed with blev påkörd because it's normally something that happens very fast and you state the result rather than describing the process (which is so short anyway).
In your other question, it was stoppad because it's singular passive. In this case, it's still singular passive - but förslag is an ett-word, so it's conjugated to stoppat.
Edit: Sorry, I just realised you found that out in the other thread as well. I'll leave my answer here in case anybody else is wondering too. :)
The purpose of this lesson is to show you a little bit about what the forms of the passive are in Swedish and give you some examples of how they are used.
This is a sentence from Swedish into English. When you translate the same sentence from English into Swedish, the answer Förslaget stoppades is also accepted. I think my short answer to gisberth above in this discussion pretty much covers what can be said about the difference.
We don't use the passive a lot in Swedish, except for a few combinations such as är född 'was born', so in a basic course like this one, the most important thing is just to recognize and understand the forms.
I get the feeling that we would be understood whichever we use. I find Duo is fairly relaxed about which I use, and I guess the way to learn the subtleties and preferred uses is wider reading. I do see passive sentences in online newspapers and they're not hard to understand.