Wow! I would have never guessed that. Is it common to use не иначе in this way?

I would say that it's not very common but still often used. It has a slight archaic feeling to it.
Full phrase ends with "как", but sometimes it's used without, especially to end a sentence:
"я простудился, не иначе".

If you consider "иначе" as "other way", the whole phrase translates to "there's no other way, but".

Hi, guys! And what about "nothing short of...".? Any ideas if it can be used as well? Thanks!

Hi, Hanna)
Hard for me to say as I rarely meet this phrase. Uly should know better.