There is a prohibition to eat from the sciatic nerve of an animal (gid hanasheh) as well as certain fats from a domesticated animal (cheilev). Before meat can be eaten, these must be removed via a process called nikkur (Hebrew) / treibering (Yiddish) / porging (English). See e.g. here and here.
As this process is time-consuming and difficult, in most Ashkenazic communities (at least outside of Israel) the entire hindquarters of the animal are instead sold to the non-kosher market.
Despite the relatively widespread belief that Ashkenazic Jews may never eat hindquarter meat, it would seem that the mainstream opinion is that they are in fact permitted to, if the nikkur has been performed by an expert as required. See e.g. this article by R. Dr. Ari Zivotofsky.
However, as noted in that article:
The practice of some communities to refrain from eating hindquarters, owing to the difficulty in excising the forbidden sections, continues to exist among both Ashkenazim and Sephardim.
My question is, are there communities out there today where this practice has the status of a full-fledged minhag hamakom (local custom) such that they would always forbid hindquarter meat, even where the nikkur was correctly carried out by an expert?
One source that I am aware of is R. Moshe Sternbuch, writing in Teshuvot v'Hanhagot vol. 1, Yoreh De'ah 418 about what he believes to be the practice in Johannesburg, South Africa (translation mine):
For us in our place [Johannesburg] this is a custom that is a 'fence' to avoid transgressing a prohibition and which cannot be annulled ... as fences such as these are a wall for the religion, and the Jewish people's keeping of the Torah depends on upholding the restrictions and fences that our fathers have been accustomed to from generation to generation, or the local custom, as it is the obligation of every rabbi to enact restrictions in his city and to enact according to what is necessary, and we are obligated to uphold the custom.
Are there any other sources ruling similarly in other current Jewish communities?