Two likely causes are autofocus not locking, or the camera’s buffer filling while it writes to the memory card.

First, test autofocus: switch the lens to manual focus (MF). If the shutter works normally in MF, the camera may be refusing to fire because it can’t achieve focus. That can happen in low light, with an AF problem in the lens, or with an AF issue in the camera body. Try another lens if you can.

If the problem still happens in manual focus, try a different memory card. After several shots, the camera stores them from its buffer to the card. If the card is slow, the buffer can fill and the camera may pause until it catches up. This would fit the “works for a few shots, then stops” behavior.

Live View focusing is normally slower than viewfinder AF, so slow response there is not unusual.

Good tests:

• Switch lens to MF
• Try another lens
• Try another memory card
• Test in brighter light

If the issue continues across lenses and cards, the camera body may need service.