An alert could not be executed for several reasons. For example, if your TV_PROTECTION parameter is enabled and TV_GAIN is set to 5, it won't sell unless the profit for that trade is, at least, 5%, even if you get a sell alert. In your case, it seems that the problem is that TV_MVTS is lower that the amount you already have.
In other words, TV_MVTS states the minimum amount that makes the bot switch from buy mode to sell mode. It doesn't buy because it's on sell mode. So, if you want to buy more before selling, just raise TV_MTVS.
Anyway your reseller should be able to help you and take a deep look into you settings in the case you need support. Hope this helps.