There are lots strange things happen when involved with FTA system installation.
Here are some common things will effect your dish signal quality or you get one channel up but not the other channel.
Shape of dish. Any bent ?
Size of Dish, a little too small?
LNBF support arm seem too short ? This will happen when you get one TP lock up but not the other TP.
Skew for the LNBF, depending where you at and what satellite you want,
Dish is not plumb, you will not get maximum signal quality on this.
Picture come and gone, this could be bad or cold soldering LNBF, or dish need readustment.
If an installer only deal with DTV or Dish network, very possible they has no idea how the FTA system work, even worst, they even don't know how to do the OTA antenna installation right.