[Crawl] Unseen air elementals?

Some air elementals seem to have fun fighting around me, I'd like
to watch and play, too, but they don't want me to join, playing
merry "You can't see us, nya, nya.", even though I'm wearing a
ring that should enhance my eysight (or maybe that's going "Nya,
nya." too).

All I do see are one friendly and two hostile air elementals,
others (friendly and hostile) are only occasionally visible. Is
that meant to be that way (them only being air and all)?

Summoning new ones (from apparent thin air) to keep me company
while the others enjoy themselves sometimes produces an odd
message, too. Here's the relelvant bits...

 Dungeon Crawl version 4.0.0 beta 26 character file.
[...]
It hits it!
It misses it.
It hits it!
Cast which spell ([?*] list)?
Summon from material in which direction?
The elemental doesn't seem to appreciate being summoned.
Cast which spell ([?*] list)?
Summon from material in which direction?
Not there!
Summon from material in which direction?
Not there!
Summon from material in which direction?
The elemental doesn't seem to appreciate being summoned.
It hits it!
The air elemental misses you.
The air elemental misses you.
It misses it.

#   #.....##.#.#.#
#   ##...###.#.#.#
#    #...###.#.#.#####
#    #...............#
######.......#.#.##..#
.........##.##.#...#.#
.........##.##....##.#
#######.........v....#
##### [EMAIL PROTECTED]
....# #..##.#....v...##
....# #...............#
....###.###..#.##.##.##
..........<.##.##....#
....##..##.###.#...#.#
#.[)#"#.##.###.#...#.#
...................#.#
[..>.\#.##.###.#.#.####

The one above me is friendly.

 S - the ring "Ehetocovovejy" (right hand)
[...]
   It enhances your eyesight.

So, what's going on here?

Thanks.

Tina