My bend just tilted it

You set a bend and the shape leaned over instead of curving. Turning the amount up leans it further. Nothing errors, and the node is doing exactly what it was asked.

There is nothing in the middle to bend

Bend, twist and bulge work by moving each point according to how far along the shape it sits. A box has corners and nothing else, so there are only two positions along any axis: the two ends. Move those and you have tilted a straight thing, because there is no middle to curve.

Give the shape rings along the axis you are bending. On a box that is Segments X, Y or Z; on a cylinder it is Height Segments. Both start at one. Six to twelve is plenty, and the app will tell you which one to raise and on which node.

More rings make a smoother curve, not a stronger one. The amount controls how far it bends.

The axis is not the one you meant

The bend axis is in world terms, and the shape's own rotation is applied before it. So putting a bent shape inside something rotated does not change which way the bend runs.

A bend along the up axis pushes the shape out sideways. If the curve is happening in a direction you did not expect, that is usually why.

Worth knowing, because the two disagree and neither says so: Set Position's axis is local, and this one is not.

Nothing happened at all

Taper and shear do not need rings, so if one of those did nothing the amount is the thing to check.

Taper's amount is what the tip KEEPS, not what comes off. At 0.99 the tip stays at 99 percent of the base, which is a taper you will never see. Come down to about 0.5 before deciding it is broken.

It curved, but the ends went strange

A bend past roughly half a turn brings the shape around on itself, and the two ends can meet or pass through each other. That is the bend working. If you wanted a closed ring, a spun profile or a curve to follow is a better tool than a bend.