Dividend transaction records are being saved as stock splits
There is not a single "Dividend transaction" in the QIF file records displayed by the original poster. All the displayed transactions are "Buy" transactions.
In a QIF file, the investment transaction "Action" value is identified by an "N" in column 1.
[The transaction record that begins with the letter "M" followed by the word "Dividends", is a "Memo" record; and the text following the "M" means NOTHING to Quicken ... it is just plain old TEXT. A Dividend transaction would be identified by an "N" in column 1 followed by "Div". And a Stock Split transaction would be identified by an "N" in column 1 followed by "StkSplit".]The original poster has not supplied enough information to determine conclusively whether there is any Quicken problem ... much less what that problem might be. I'm not aware of any such issue being reported before.
Here are the contents of a QIF file exported from an investment account in one of my test Quicken (R30.14) files (each of the aforementioned transaction types (Action Values) is shown below):
!Type:Invst D1/ 1'20 NBuy YA Stock I10 Q100 U1,000.00 T1,000.00 M This is a "Bought" transaction - the contents of this specific (Memo) record are meaningless to Quicken ^ D6/30'20 NStkSplit YA Stock Q20 M This is a Stock Split transaction - the contents of this specific (Memo) record are meaningless to Quicken ^ D12/10'20 NDiv YA Stock U25.00 T25.00 M This is a Dividend transaction - the contents of this specific (Memo) record are meaningless to Quicken ^