Your example did work, but in my case I've used a sub routine that sets up the tiles. The very first thing I tried was the paste sprite, but after it exits the sub routine and sync, or even if I sync before the return all the pasted sprites disappear. To fix that problem I cloned some blocks that I needed a bunch of times then placed them in my 2d space with the sprite command and they stayed on screen without disappearing. Almost sounds like a bug to me.
To see how it disappears like it does for me I'll use your example code.
sync on
sync rate 0
cls rgb(255,255,0)
get image 1,0,0,50,50,1
sprite 1,-50,-50,1
for x = 1 to 5
paste sprite 1,x * 100,300
next x
sync
do
sync
loop
-it would disappear this way too-
sync on
sync rate 0
cls rgb(255,255,0)
get image 1,0,0,50,50,1
sprite 1,-50,-50,1
for x = 1 to 5
paste sprite 1,x * 100,300
next x
do
sync
loop
[edit]..I just tested your example in a similar way within my do...loop ran the game and it drew the pasted sprites and then afterwards the pasted sprites disappeared. Those pasted sprites were the last thing drawn to the screen which would make you think they'd stay fine, but they keep disappearing.