edit: Problem has passed. As stated, refreshing, relogging and switching browsers did nothing to solve the issue. However, now as I return after a few hours offline time I find that the offer has advanced to the trade at some point. At least all 4 lots show up as sold in the history tab, and the occupied empty rows are gone. Even so, the devs may want to look into this, in order to prevent the problem from occurring in the first place.
original: I intended to sell water in 4x 20.000 lots, having a total of 100.000 in stock. When I posted the trade, the 'selling' tab flashed filling all available slots with empty rows. Free rows are usually blank; in this instance, a coin sum was added to the sides of the rows, as if indicating that they are paid-for offers. All this with just pressing 'place offer' once. I've highlighted this anomality in red in the enclosed screencap.
While I didn't pay attention to the amount of coins I had prior to posting the trade (and thus can't say if the rows really cost me coins or not), I do know how much water I had. After this bug/glitch, my stock had dropped to 20.000, so the 80.000 in total that I had posted as an offer was gone. Refreshing, relogging and switching browsers have not changed the way these extra rows look like, nor has the water been returned to the warehouse. The trade history has recorded none of this happening.
In essence I lost 80.000 water, and have 156 gold coins worth of empty rows in my 'selling' tab, which may or may not have been subtracted from my stock.
trade bug.jpg