The problem is IRCC won’t always understand circumstances. If you have citizenship file in process, they expect you to be present inside Canada. It’s completely their discretion to not to return your file as you have missed your test twice.I am out side of Canada and due to circumstances I missed my test invite and its my second time that I couldn't reply them on time what they can do now will they cancel my citizenship application or they can send next test invite
I’m quite sure they’re scheduling knowledge test for people who are not in Canada thru Teams on case by case basis.
I think, your letter of explanation should include everything what’s preventing you coming back to Canada at this time and why you should be allowed to take knowledge test from outside of Canada.