I think that there must be many - still, many were absent... Probably staff reduced to liaison officers...
Of the important countries that took part in WW2 I see one is missing-
Siam/Thailand
They have had taken active part in the WW2 - I think they were in war with France in Indochina at the time...
I think that Albania and Montenegro must have had some relationships - perhaps attached to missions of Italy and Croatia.
Also, there must have had been many 'governments' of 'non-existing' states. I have on my mind ex Soviet republics, from Baltic to Caucasus, including Russia, Ukraine, White Russia, and many more (Lithuania, Livonia, Estonia, Armenia, Georgia, Azerbaijan...)
I think that list is surprisingly long, it probably included even British and Americans...