The Broadway play “Stick Fly,” directed unevenly by Kenny Leon, offers views on race and class from an upper-class Black family, but soon devolves into a sitcom with little dramatic punch. Lydia R. Diamond’s modern drama loads on several issues and some family conflicts in the first act, but fails to resolve little by the end of the long second half.

To make matters worse, lead actor Dule Hill does not fill out one of the central roles as the youngest son, and others among the cast, except for Mekhi Phifer and Condola Rashd, don’t deliver fully realized performances.

A beautiful set boasts an ornate oak ceiling with chandeliers and a Romare Bearden painting as the upscale vacation home of the LeVay family, where the sons and parents normally gather for a weekend get-together. Kent (Hill) arrives with his fiancee, Taylor, played with a few insecurities and unsupported flourishes by Tracie Thoms.

The eldest, arrogant son, Flip (Phifer), a plastic surgeon, comes next and congratulates Kent on his book, which is soon to be published. Flip enters in advance of his girlfriend, Kimber, to prepare the family to receive her because she happens to be white-or “Italian,” as he puts it.

Taylor clashes early on with Kimber and with her fiance along class lines by being too outspoken, presumably due to her “lower” middle-class upbringing. She voices feelings of abandonment by her father, who later remarried and raised another set of children. She gives Kimber a tongue-lashing because she assumes the status of an expert as she breezily talks about working with poor Black children in the inner city.

To add to the conflicts over class, the maid’s daughter, Cheryl, tries to please everyone as she fills in her mother’s shoes until she can arrive. But no one takes the time to listen to Cheryl about her concerns about school life in the early scenes.

Rashd, as Cheryl, is one of the bright, fully formed performances in this overwrought work. Phifer provides sparks of his own, playing true to the self-centered, sexist older brother. Ruben Santiago-Hudson does his best to bring life to a stereotypical father role.

Unfortunately, the play is too long and stumbles under its own weight in the second half. Cheryl reveals a major family secret after intermission, adding another major conflict. The playwright should consider cutting out the waste to sharpen the focus of this drama.

Rosie Benton as Kimber tells a long, tragic story about a fictitious sister that could easily have been cut. Her efforts at comedy later in the play further confound the issues and whatever point she intends to make.

Original music by Alicia Keys is a welcome addition and plays quite effectively as a bridge between scenes. Scenic design by David Gallo allows players several staging areas and fluid movement onstage. Lighting by Beverly Emmons proves effective in showing the passing of time from morning to afternoon and night.

“Stick Fly” continues an open run at the Cort Theatre, 138 W. 48th St.