QMac has worked better than QWin for Fidelity money market funds, but I just ran into this problem:
I bought some shares of FZDXX. This is NOT one of the money market funds you can use as cash - it's a premium fund.
I maintain QWin in parallel, and it shows, properly, the purchase of the shares. I spent all my cash (which is in FDRXX money market fund), so it correctly reduced my cash position to 0 and added the right number of shares of FZDXX.
The buy transaction doesn't appear in QMac, so it shows no increase in shares of FZDXX, and no change in the cash position.