I hesitated to try and answer because your description of the problem is not very clear or well worded. I can't get a complete picture.
However, a MikroTik DHCP Server (could be more than one configured) can be assigned to a particular interface. An IP Pool can be assigned to a particular DHCP Server. If the ports are bridged, the DHCP Server should be assigned to the Bridge port. Check all of these settings.
When you said you turned it into a bridge did you mean LAN ports or did you bridge LAN and WAN? As I said before, not very clear.