When mixing your cookie dough, it’s important to use butter at room temperature. Butter that is too warm or melted will similarly prevent your cookies from holding shape at all.
Cold butter won’t only mix into horrible chunks, but it will result in strange consistencies as the butter fails to properly bind with the sugar in your dough.
Overmixing your butter and sugar creates a huge risk of cookie spreading. This can result in essentially melted butter that is liquidy instead of creamy.