Via hole wicking was a common problem in the early days of surface mount reflow. Poorly trained design engineers placed via hole either in or too close to pads. During reflow the solder was drawn down the hole starving the joint area. Via or through holes should be a minimum of 0.010" away from solder pads and connections should be either 0.006-0.008" in width.

It is possible to place vias in pads provided the size is small enough to block before all the solder volume is lost. This technique generally increases the cost of the printed board.

Via placement in pads or too close to solder lands is an old problem but still happening in the industry due to poor education of engineers.