I recently started setting up the shops inside of my residence. When I started setting up the dye shops, I got the message "Another players shop detected!" and the sign would pop back off of the ground. So far I can't find any reason why it would do this. Hoping somebody else might know how to fix it.
Still having the problem. It actually happened in a bunch of other locations after I posted this so my whole dye market is dead till it's fixed. No hurry to fix it though since I doubt selling dye will be very exciting.
I figured it out! As you can see in the picture in the original post, I have a sign sitting below. (it's to tell the dye color) When I removed this label sign, the bug ceased to happen. Hope this helps anyone that might have the same issue in the future!