Rick,
This is normal behavior.
Your first images were in RGB mode even though they were monochrome. They have three channels of color, something to balance to make a white of some color.
Your current images are in grayscale mode, only one channel-gray. Nothing to balance, so the tool is inop with images in grayscale mode.
Change the image mode to RGB Before you import into LR and you will be able to give them that warm look like before.
HTH
Rich