The Palestinian refugees issue is a political one.

The middle east had several nationalities striving for independence in the mid 20th century, in an area controlled by the British Empire. Documents and agreements defining borders ad land divisions were made -and thus Arab nations in the area gained independence in the form of new states: Syria, Lebanon, Jordan, Egypt, and one Jewish nation - the state of Israel;

The only nation in the area declining these agreements were the Palestinians - and thus there was a collective war, which ended with the Palestinians losing most of their land:
some was taken by Jordan, some was taken By Egypt, some was taken by Israel. Arabs left in the territory of Israel were allowed Israeli citizenship, as well as being elected to the Israeli parliament, similarly to Jordan.

Palestinians kept revolting against all those countries. A Palestinian assassinated a Jordanian leader, and Palestinians hijacked civilian planes, until the Jordanian army started a full-on war against them which ended in about 4000 Palestinian casualties and the fleeing of the Palestinians into the neighboring country Lebanon, establishing their military bases in the once-peaceful city of Beirut.

Eventually Israel took over those lands from Jordan and from Egypt, and both signed a peace treaty with Israel, removing responsibilities from taking care of the Palestinian refugee problem and shutting-off completely their border with the Palestinian territory.

Israel left the border opened, controlled by the Military. Palestinians were allowed to pass into Israel, and work there.

Palestinians kept fighting, revolting, executing dozens of terrorism acts against civilians, Israeli-Jewish as well as Israeli-Arab, resulting in hundreds of deaths. While the leadership of the Palestinians was directly declaring its primary goal as completely annihilating and removing Israel from existence, Israeli withdrew forces from Gaza, but a year after a violent organization took control of it, executing any Palestinian opposing to it (also gays...). The fight is on-going ever-since, where the Israeli military protects its state borders, allowing some Palestinians to pass, while entrance for Palestinian territories by Israelis is completely forbidden, and in the rare occasions if an Israeli passes by mistakes he is lynched and massacred.

The point is that this situation doesn't necessarily have a "good" or "bad" side - and by "choosing" a side you are not "using" your power to influence, as artists and musicians - but rather you are abusing it.
By taking a side, and choosing to cancel performances in-front of fans - who are not actively participating in this political issue, and are most likely not against Palestinians finding their own land and gaining a better life - you do NOT promote peace and solidarity and understanding, but rather the opposite - segregation, anger, war...

Also, once you start taking political sides in issues like this, there is no end to it - the US government recently canceled a 200 Millions dollars for the Palestinians after they declined (again) to review a peace plan offer from the US -

would you ban shows and performances in the US in-front of American audiences now? Why not?