Did you prune them too late in the season?

Do you know the difference between foliage and flower buds, and are certain you have flower buds that haven't opened? I don't mean to sound too elementary, not everyone can tell the difference :)

Cold weather can kill flower buds. (Usually you see brown buds in the spring) Cold snaps in the fall after buds are set or freezes in spring that follow a period of mild warmer weather can damage buds.

Drought is another possibility, ground too dry can cause buds not to open.

Bud blast - fungal infection, the dead bud will be covered with short hair-like structures, I don't think you would mistake them for normal healthy buds.

Or, if the buds are present and healthy, are they just later this year with the exception of the one? Our spring has been chilly here, many things are behind 'schedule'

April- No, I didn't prune them at all.
Morz8- Yes, I know the diff. between buds and foliage- I have been gardening for many years specializing in roses. I don't know much about rhodies though. It's almost as though the buds have been suspended in time, except for one that is showing color. I doubt if the others are just later in developing... there doesn't appear to be any fungal infection and we've had a lot of rain. Thanks for your input, would appreciate any other suggestions.

I think if they don't look brown or diseased, I'd give them some more time. If after a couple of weeks you still see no change, if it were mine, I'm sure I'd be tempted to remove a bud, cut it lengthwise from top to bottom with a sharp knife, see if any explanations for failure to open are indicated there.