We're really sorry for all the hassle. Are you applying the camera profile while importing the images into Lightroom? If yes, then please set the develop preset to "none" on the import window. Once the images are imported into Lightroom then, you can apply camera profile as required.
Also, please update Lightroom to 7.4 version via Creative Cloud desktop app and let us know if that helps.
Have you tried the following: Select all the images. Change the camera profile of the most selected image. Then press the Sync (in the Develop Module) or 'Sync Settings' (in the Library module) button and in the dialog that comes up, uncheck everything except 'Treatment and Profile'.
This odd behaviour is now fixed in LR v7.4 (Camera Raw v 10.4).