You absolutely must use a thermometer capable of registering high temperatures and cook your syrup to hard crack stage. I am a professional confectioner and make hundreds of lollipops weekly, and occasionally, I will accidently remove a batch of syrup from tbe heat before it reaches 300°. In that instance, the lollies fail to set to hard crack every time. If your thermometer is reading 300° but your lollipops are not hardening, calibrate your thermometer. There are many good sources on how to do this, depending on which type you own, all over the Internet. Also, make sure you measure using weight instead of volume. It is much, much more accurate. King Arthur Flour is just one source with a volume to weight conversion chart in both oz. and gr. I highly reccomend you convert your pastry and candy recipe ingredients to grams. Do not stir your syrup beyond the point that the sugar, glucose/corn syrup and water are all dissolved and mixed, and use a pastry brush to swipe water around the sides of the pan if sugar crystals form. Go lightly on that water, using only enough to dampen the brush. Finally, humid conditions absolutely affect hard candy, just the way it affects meringues, macarons and spun sugar, as well as other types of candy making. Do not make any of these items when it is damp or humid.

The temp of the sugar should be around 300 F. or more. Did you set the temp to 160 Fahrenheit instead of Celsius? If it was celsius, it should be rock hard. I make sugar wax and the recipe is similar. (The difference is that wax requires more lemon juice & lower temp.) In order for the lollipops to come out hard it needs to be heated on max and boil to 300 F. When it hits that temp, I still keep it on the stove until the texture is very thick. I work quickly after bc it'll harden & shatter.