I have this issue too.
I search the answer to fix it, almost answer I found is "turn off your device and then turn on and loading friends list again. if fail, try again tomorrow"
but it not work for me. TTATT
thank you for adding me
but I can't load friends list ( I hate this issue OTL -- actually I can load some but not all), so I can't give you back
then I try to turn off device anytime for loading it.