Darrell,
Yes, the addition of Text-based editing has produced some changes. But in this case, they will be worth the adjustment.
There are now 2 types of transcripts: Source media and Static (sequence). If you manually or through the auto-transcribe create a transcript for a Source media file (i.e. a clip, whether in a sequence or not), you can open that clip in the Source Monitor, and when you immediately switch to the Transcript, you can edit speaker names.
If you add that clip to a sequence, and have the timeline/Program Monitor view active, and go to the Transcript tab and try to edit the speaker name, you get the error message you saw. Just double click the clip (to open in the Source Monitor), and you can edit the speaker name in the transcript.
If you select the timeline/Program Monitor, and click the 3 dots in the Transcript tab, you can pick "Generate Static Transcript." This is the "old" style transcript. For this one, you can edit the speaker names when the timeline/Program Monitor is active.
Stan