In a recent podcast interview (I can't find it now, I listened to it a few days ago) her husband Bruce Sudano (1980-2012) discussed Summer's time at Geffen. He really had nothing but great things to say about David Geffen, and put the blame of her career melt-down in the 80s on the label.
Sudano explained Geffen was excited to get Summer on his new label (for a record-breaking amount of money) - he was able to sign up 70s heavy-weights Elton John and John Lennon after she signed, and got his label off to a great start in 1980. He was disappointed that 'The Wanderer' didn't top the charts , but Sudano explained the 'phenomenon' of 1979's 'Bad Girls' doesn't usually repeat itself for an artist, which Geffen was aware. Geffen thought the answer was for her to work with Quincy Jones for the second release (which is why he ditched the pop / disco album 'I'm A Rainbow' without even listening to it). Geffen wanted to give SUmmer a more 'R&B' sound, which he did - but it also wasn't the hit he was expecting.
By 1983 - 84, Geffen stepped away from the 'every day' management of his company and his artists, leaving all those responsibilities to 'a younger team' without experience. This team were now responsible for releasing singles, albums, promo work, etc. and finding new talent. They paid no attention to the older artists like Summer and Elton - and brushed them to the side. Summer and Sudano wanted to sit-down with Geffen at that point, but he was nowhere to be found - he really had absolutely nothing to do with his record label anymore and was involved with other media / entertainment. Any complaints or concerns were handled by this revolving door of personnell within the company (I'm wondering if they were muscle-hunks from the gay bars that Geffen had given these positions to back then). They could tell this group was looking for younger talent, and Summer - now in her late 30s - didn't fit the image they wanted.
In 1988, Summer presented "Another Place and Time" to the label, and they wouldn't release it. They told Summer she could leave the label without fulfilling her remainder on the contract, and she could take 'APAT' with her - they didn't want it. So she signed with Atlantic and they released it.
When the album and the single became a hit in the summer of 1989, they got a call from David Geffen wanting to know why she left the label and why his label didn't release this. They finally met up in person, and had a very long conversation with him - how his young team had treated her, and how they mismanaged her career since he left five years earlier. Sudano said Geffen insisted he knew nothing of what was going on, and trusted this young team with managing his label. He was sad that Summer left the label, and wished the two of them well. Sudano said to this day, he and Geffen remain on friendly terms - and he and Summer never blamed him personally for the mismanaging of Summer.
If I come across this podcast, I will post it here. (I believe it was done in Italy).