I'm starting to wonder if the TYPE of account at Fidelity impacts this.
Fidelity allows individuals to open mutual fund accounts and/or brokerage accounts. The taxable joint account with my wife is brokerage-type, as is my Rollover IRA, her Rollover, her Roth & her SEP-IRA, while my Roth and my SEP are mutual fund accounts.
The mutual fund accounts have neither a cash position nor a MMF, while all of the brokerage-type accounts have a cash position (recorded in Q as "cash" for the IRA accounts and as a linked cash account for the taxable fund) (and yes, I realize that I COULD merge the linked cash account into the taxable portfolio, but since this is our primary checking account, I like having it separate).
I can easily envision that Fido might download one type of record (a ReinvDiv) from a MF type account and another (a Div) from a brkr account -- even if the actual cash in both circumstances originated from FDRXX or SPRXX --, thus possibly explaining the discrepancies in experience being reported here.
db