I'm suddenly locked out from some protected friends

I'm suddenly seeing My updates are protected. Request to follow me when I click the icons of some - but not all - friends with locked updates, although we mutually agreed to follow each other weeks ago.

Example: paganinijones - whose updates (seen yesterday evening!) don't currently appear in my timeline, either.
My @paganinijones tweets at that time are also currently missing from my timeline!

This is partcularly inconvenient because paganinijones first joined Twitter in order to be in better contact with me!

The number of my friends has decreased (I'll report this in the proper thread too), though I've not yet worked out who's missing:

Following: 35 (should be 41, I think)
Followers: 19 (should be ca. 28)

In two recent tweets, timtfj reports a more extreme variant of this problem:

@GKeast Not sure what's going on - suddenly I only have one follower & can't see your updates!
Current sitn: @Eridanus listed as only follower/ee; get ppl's updates but protected ones have "only giving updates 2my friends - add me"

I suspect this problem is in part related to the follower/following counts issues described in the Twitter status report Updated follower/following counts and on the metaTwitter (Get Satisfaction) thread Followers and Following are all gone - when will this be fixed?.

On Twitter I'm Eridanus too.
I haven't added or updated mobile devices in months.