It happens when you put a string with a left-handed twist on a left-handed bow, or right-hand twisted string on a right-handed bow. The torque of the bow works in tandem with the torque of the string, causing the bow not really to twist, but to "bow" to one side. The stringmakers finally admitted to this tendency, and went on to produce a public-education video, to prevent folks from falling victim to the string/bow torque inherent to the design under these circumstances.
The way to make the string work, if you find yourself with a string twisted the same direction as the bow's handedness, is to put the string on upside-down, thereby reversing the twist orientation. Other than having to unstring from the bottom limb (not disadvantageous, gravitationally speaking, as you will find that your string stays put without a string keeper, provided you keep the bow upright), there will be little or no change in your shooting routine, and you can use the string with no risk to you or your bow. This being fairly common knowledge, it is not surprising that merchants do not bother to market strings that are specific to the orientation of your bow. Sticklers for tradition will, of course, want the proper string because of the difference in top and bottom loop sizes, as they do not want to be seen unstringing their bows "incorrectly". So, right-handed shooters seek out right-handed stringmakers, who naturally produce right-hand-twisted strings. It is exceedingly hard for a left-handed person to make a right-handed string, and vice-versa, and a truly ambidextrous stringmaker is in the highest demand.
Double-shelf bows, by the way, necessitate the use of the endless string type, which is never to be twisted either direction.
If you wish to learn more about the dangers of Flemish twist strings, if handled improperly, I will give you the name of that video that went with the PSA when the stringmakers decided that covering their assets would be better than a possible flood of lawsuits and reimbursing thousands of archers for their ruined bows. The video came out a couple of years ago, and is called "Doing the Twist".
Glad to help.
Killdeer