I see there is a bit of confusion with that issue. To the best of my memory, this is what happened:
With
Fear of the Dark, Maiden first used a different artist from Riggs, but did further collaborate with him until the
X-Factor era. My personal theory, but don't cite this as a fact, is that they dropped him because his work at that time plain sucked. I can't find the quality of his 80's work in pictures like
A Real Live One or
Hallowed Be Thy Name, and I think he got really tired of drawing Eddie. But this is opinion, not fact.
Riggs did sporadic work for Maiden, like the
Virus LP single, the
Best Of The Beast cover, the
Angel And The Gambler single and some other work that did not get very much attention. When Bruce and H returned, Maiden wanted to go full circle and got Riggs to paint the cover for the new single. However, according to Riggs, they told him the new album would be called
The Wicker Man, and he prepared artwork based on that concept. In the end, however, Maiden only used the "cloud Eddie" from that artwork and dropped the rest, replacing it by the CGI city. Riggs got pissed off by this and said that he would never work with Maiden again. Incidentally, the actual
Wickerman single used artwork by Mark Wilkinson.
This is the original artwork he had done:
Although some undated Riggs artwork appeared in the
Eddie's Archive box set, none of Riggs' art appeared on official Maiden releases from
Rock in Rio on, although the
Matter of Life and Death tour used a new Riggs painting as a backdrop for
These Colours Don't Run. This picture also appeared on the cover of Riggs' biography, which was promoted on the official Iron Maiden website, and there were some other activities in which he was involved. I guess it's safe to say they settled their differences, but I wouldn't put my money on new album covers by Riggs.