I am not entirely sure if you are using the correct, current name for "Monastir".
After doing some research on Bulgarian annexation of Macedonia in WW2, I had a hard time finding a city named "Monastir" on any WW2 map of the region.
Instead, I found "Bitola"
https://www.wikiwand.com/en/World_War_I ... _WW_II.png
After digging a bit further....
After WWI, it was officially known by its Slavic name--Bitola; a name dating back to the short period of Bulgarian occupation.
The official name of the town today is Bitola, and it is so listed in the (US) Holocaust Museum among the Jewish communities destroyed by the Nazis and their sympathizers.
Bitola (bēˈtôlə), formerly Monastir, city, S North Macedonia. It is a commercial and industrial center for the surrounding agricultural area. Bitola was a major agricultural center in Roman times. Later settled by Slavs, it became a bishopric in the 11th cent. In 1395 the Turks conquered Bitola, which became an important military and commercial center in the 15th and 16th cent. The city suffered much damage during the Balkan Wars (during which the Serbs took it from the Turks) and in World War I. Bitola is noted for its numerous mosques, churches, and a former Turkish market.
From 1382 to 1912, Bitola was part of the Ottoman Empire, at which time it was called Monastir.
Bitola, or also known as Monastir during the Ottoman Empire, was and still is an important town:
