Wells Fargo CMS Oddity: Last late payment 8 years ago

Here is your anomalous CMS output for the day: Background: I have one account on my credit report that remains from my BK7 in May 2016. It had no lates when it was closed after I filed. When AMEX closed it my payment history (the grid) changed from all good months to no report going back two years prior to closing. The date for removal listed on my Experian ACR is May 2023. This morning I looked at my new EX9 score from Wells Fargo. I started poking around and saw this: WF EX9 Payment Hist.png 8 years since my last late payment? Hmm. That's not right. It should be May '16 when the account was IIB. (The 30 day and 60 day lates noted here are the assumed lates built into how IIB accounts are reported. They didn't actually occur.) Let's look at what WF is showing for the account. WF EX9 Payment Hist2-3.png As you can see, the grid shows no payment history after May '14 until May '16: 8 years ago. So that's where they pulled it from? Lets look at what Experian shows. I happen to have an Experian report from the same day as the date of the pull by WF. WF EX9 Payment Hist4.png The grids match. But: My understanding of how the data is used is that the grid is a representation of other data and any other representation of the data would not be derived from the grid. So where is the WF CMS pulling the May '14 date from? No data is not "late". And May '16 is much more recent than May '14. Very odd. Here is the account as it appears on my Experian ACR: WF EX9 Payment Hist5.png The obvious moral is don't take CMS output (beyond actual FICO scores) too seriously. Thoughts?