A strong producer’s hand has saved many a filmmaker from one’s worst impulses, and that’s what seems to be missing from the promising, well-cast and handsomely mounted romance “Sylvie’s Love.”

This star vehicle for Tessa Thompson has a solid supporting cast, lush settings and a script that made many a 1950s romantic melodrama sing. Remember the films of Douglas Sirk, or “Far from Heaven,” which was Todd Haynes imitating Sirk.

But at some point “promising” turns indulgent. And the longer this “Love” goes on, the more contrived and bloodless the obstacles to the romance become.

Thompson has the title role, a daughter of the Harlem upper class whom we meet, perfectly-turned-out, waiting for a friend to join her for a 1962 Nancy Wilson concert at New York’s Town Hall. That’s where she runs into Robert (Nnamdi Asomugha), an old flame, a jazzman she fell for in her youth.

A long flashback tells the story of their five-years-past romance, sax player Robert meeting debutante Sylvie at her dad’s (Lance Reddick) record shop. She’s engaged to a doctor’s son in the service, stationed in Korea.

But she flirts by giving him a Thelonious Monk record. He flirts by applying for work at the shop, and putting her on “the guest list” at the club where his combo is playing.

Her pal, Mona (“Mona LISA, like the painting!”) wants to know “Is he cute?”

“I hadn’t really noticed” doesn’t convince Mona (Aja Naomi King) or us.

Thus, the summer of ’57 becomes a tale of how long she can resist this somewhat chivalrous (He knows she’s engaged.) tenor sax player, and how that will play into their futures.

Sylvie is a TV addict who longs to produce television shows. Robert is a member of a quartet just waiting to be discovered at the end of this Golden Age of Bop jazz. Meeting the rich, connected European connoisseur/manager nicknamed “The Countess” (Jemima Kirke, terrific) seems to send Robert on his way. Sylvie? She’ll have some big decisions to make.

That long flashback ends and the story returns to the soap operatic 1962 present, and the complications that came between them back then have compounded themselves, and multiplied. Can they ever be together?

Musician turned actor turned writer-director Eugene Ashe knows this turf well, and the attention to detail here has a “Mad Men/Mrs. Maisel” sheen, New York at its “Cafe Society” peak.

The musical threads of the story, young Sylvie foreshadowing America’s coming disconnect from jazz and embrace of rock’n roll and soul, the lure of Paris for every jazz musician of the age, are spot-on.

There’s a lot of jazz and over-played period-appropriate pop on the soundtrack,

The film’s debutante milieu (Erica Gimpel plays Sylvie’s prissy, charm-school director mother), the perils of “a young lady” carrying on with “a young man her station” is both old fashioned and accurate. The unspoken class divisions between lighter skinned African Americans (Sylvie, her mother, her fiance and his family) and darker skinned folks is suggested.

And Thompson, of the “Creed” movies and a popular member of the Marvel Universe, dazzles in scenes where Sylvie fights her impulses and yet loses herself in the guy his band nicknames “B-flat” when he plays a sultry sax solo.

But saying “Sylvie’s Love” is slow is an understatement. And Ashe takes that indulgence, which suits the “old fashioned” nature of the romance, and starts shoving every melodramatic device in the book into the meandering proceedings.

Mona’s involvement with the nascent Civil Rights Movement is an interesting garnish that is left undeveloped. Hints of the racism the characters deal with are barely touched-on, as is the sexism that a working woman like Sylvie would have faced in almost any profession at the time, especially TV.

Sylvie’s baby steps into TV production, working on a TV cooking show hosted by Wendy McLendon-Covey (a hoot), hints at a TV series that might have been, which might have been this project’s original plan.

Dramatically, this is so flat that any little hint of wit (like McLendon-Covey, and Kirke) stands out as a reminder of what the story is missing — tension, suspense and pace.

And rare is the conversation or monologue — characters launch into a couple of those — that lives up to the production values or the cast. The pleasant “getting to know you” banalities and brittle moments of insult are generic, not quotable.

“Sylvie’s Love” comes off like a novel idea given every chance to shine, but let down by a maudlin TV movie script that needed polish.

MPA Rating:  PG-13 for some sexual content, and smoking

Cast: Tessa Thompson, Nnamdi Asomugha, Lance Reddick, Aja Naomi King, Jemima Kirke, Eva Longoria, Tone Bell, Erica Gimpel and Wendy McLendon-Covey

Credits: Scripted and directed by Eugene Ashe. An Amazon Prime release.

Running time: 1:56