I just experienced this same issue with Gemini. I pasted a text message thread into Gemini (Pro, Thinking, Flash – all are affected) and it was misattributing dialogue. It said Alice said x, which Bob had said; it said Bob said y, which Alice had said. This was a two person dialogue and clearly marked with:

Alice: x Bob: y Alice : z ...

While the analysis was mostly coherent with the exception of said misattributions, I filed away the mental note that this misattribution error happened frequently in these type of exchanges.