Getting "Blocked" in Blind Pick chat for no reason

I play Blind Pick a lot, (since getting Top/ADC in Dynamic Normals is impossible) and whenever I wanna go top or ADC, I get this "Blocked" box in chat and I can't type at all for a good ten seconds. By then, everything is called and I'm forced to support. Why am I getting blocked in Blind Pick chat for what seems like no reason? I have all-chat disabled and I only ping and communicate team-based things.