my experience with microsoft apps on mac is, that if you have a lot (really a lot) of fonts installed on your system, Word and PP does not load all of them. This could explain why your font is recognized on your MacBook but not on your iMac. Maybe have a look how many fonts are installed on the iMac, and if the number is significantly higher than on the MacBook, try to deinstall fonts on the iMac.
see also this topic: