You do face issues running a regular middle/guard relay. My IP is tainted from overzealous sysadmins looking up Tor related IPs and seeing mine because middle relays are public knowledge. I am banned from a lot of places for simply being a middle relay.
Your ISP doesn’t give a fuck, it’s not legal trouble. It’s just overzealous sysadmins blocking anything that seems sus. I am permanently banned from most SoMe, for example, for having abnormal network activity but none of it is illegal.