anonymous call blocking

I haven't been able to receive calls from my sister since she moved.  The calls are on my call log as Anonymous. When I checked my setting, I see checked "Block Anonymous Calls." Trouble is, a week ago I initiated  *87 with the voice confirmation that this was disabled and I then confirmed in the settings that it was unchecked. Now it's back. What happened?  Also, if i select the option from this Anonymous call in the call log to add my sister to contacts, will that override the block?

I had the same problem with my doctor's office suddenly when they never used to be blocked What is changing?