It sounds like you installed the 32bit version of the plug-in. 32bit plug-ins are loading using BitBridge. The standard VST header is not displayed for bridged plug-ins unless the plug-in is opened with the ALT key held down. Then the standard header opens in a separate window typically behind the plug-in UI.
Other ways to determine if a plug-in is 32bit.Tthey are shown in green in the browser. The plug-in name is appended with
(32-bit) in the browser and menus.
You should remove the 32bit dll from the VST scan path and replace it with the 64bit version.