<picky>you said it was on line 209 (217), not 208 (216)</picky>. We can still be picky about that. Fact remains line 208 (or 216 for sprite mode 2) disables the sprite (and all sprites with a lower priority, as stated in the official VDP manuals. Line 209 (or 217) is used in BASIC to move it out of the default display part. That might be another confusion apart from the sprite being generated with 1 line delay.

About the sprite collision: ro, have you tested if the sprite collision is disabled in the left and/or right border, with the Early-Clock flag for instance?

picky my ASS! (I didn't say it was on line xx... I said it was on ANY of earlier mention lines )
... right, my bad. sorry . . . (sight) Atleast now, indeed, we got a clue why sprites tend to disappear.

<picky_explanation>You know what it is? If you fill the first byte in the Sprite Attribute Table (Y-coordinate) with 208 (sprite mode 1) or 216 (sprite mode 2), it'll disable. But in fact, the absolute coordinate of that sprite is then 209 (sprite mode 1) or 217 (sprite mode 2). That's because the sprite layer has a latency of 1 line compared to the real screen. But that's already stated elsewhere in this topic </picky_explanation>

It simply looks it was put on line 209 (217) while in fact it was put on line 208 (216), just because of the 1 line latency.

Yeah, thaz what D said allready (hey, can you actually SEE line 208? as in do you recognize line 208 from 209. thaz cool!!)

You can draw a line on line 208 (or 216 is sprite mode 2) and R#23 it in the visible range. and move a sprite to that line.