KTVI had lousy news ratings in the late 1980s, as stated in my post above. I'm not sure how well ABC programming performed, but ABC's St. Louis ratings must have been a bit of an issue for ABC to talk to Koplar.
KTVI nearly lost the rights to "Nightline" around 1990 or 1991. KTVI had just gotten the rights to "The Arsenio Hall Show," which KTVI planned to air at 10:30 (or 10:35). Paramount (Arsenio's syndicator) came out with a companion show to Arsenio called "The Party Machine with Nia Peeples," which was designed to follow Arsenio. KTVI planned to air the Nia Peeples show at 11:35, delaying "Nightline" to 12:05. However, ABC had a made a rule that ABC affiliates could not delay "Nightline" by more than an hour. KMBC in Kansas City and KSAT in San Antonio (and maybe one or two other stations) were granted exceptions because those stations had aired "Nightline" at midnight since the show's inception.
KTVI initially stuck to its guns and planned to air the two syndicated shows back-to-back. Briefly, it looked like "Nightline" wouldn't be seen in St. Louis unless ABC could get the show on KPLR or KDNL (and that seemed somewhat unlikely). However, KTVI finally relented and stuck "Nightline" in at 11:35 between Arsenio and Nia Peeples.