Are there any requirements to support national liberation from a ML perspective?

Given my ventures into seperatist areas in Europe, I was left with this question. Does a national liberation movement need to 'tick the left wing boxes' so to say for ML's to consider their support, or is support given regardless of political stances?

One movement in particular that caused this question to arise is the Flemish independence movement which is almost entirely filled with right wing nationalists. I do not support their movement. But why? If they wanted to be independent, should I be against that based on their politics? Is that a valid thing to do?

The same thing can be asked with regards to the Basque movement. Should I support them because of their wish to independence regardless of their more left leaning ideologies? Or should the politics be entirely irrelevant in this?

What do you think?