Ok, I took a look and indeed my wallet was full of dozens of tiny inputs no greater than .1 Dash. I decided to consolidate them by sending a transaction to myself, so now I have one input with 2.61 Dash. I started mixing, 3 denominations were created then it stopped. After a while I checked the debug log and see the successful denominations, but then eventually similar errors to before:
2017-02-25 13:41:29 CreateDenominated0 nValueLeft: 0.001643
2017-02-25 13:41:29 keypool reserve 1251
2017-02-25 13:41:29 CreateDenominated2: nOutputsTotal: 0, nValueLeft: 0.001643
2017-02-25 13:41:29 CreateDenominated2: nOutputsTotal: 0, nValueLeft: 0.001643
2017-02-25 13:41:29 CreateDenominated3: nOutputsTotal: 0, nValueLeft: 0.001643
2017-02-25 13:41:29 CDarksendPool::CreateDenominated -- Error: Transaction amounts must be positive
As far as I can tell mixing is broken in 12.1, and that seems like a pretty big deal since private send is the main feature of the currency. If you say the amount of 2.61 Dash is too small I would say:
1) The application should give me feedback that is a problem and not just quietly throw errors and do nothing on the surface.
2) 2.61 Dash may be small today, but it won't be for long at the rate Dash is appreciating. If at some point Dash become worth as much as Bitcoin is now (>$1,000 at the time of this writing) that would be pretty lousy to say $1,000 worth of Dash is too small to mix.
One last remark is that the dozens of inputs I had were mostly from a single 2 Dash ShapeShift transaction that sent a series of inputs each no larger than .1 Dash, so if that's a problem for the wallet and/or network to manage, then there's a bigger problem here.
It's not like I'm really all that concerned about the privacy of a couple Dash. I'm just trying to see if things work in 12.1, and it appears they don't. At least not with a modest sized wallet. I've uploaded a couple more log files if you're interested. (There's 2 because I stopped Dash, rename the original ".old", then restarted)
Thanks.