The strange tale of J.C. Jackson’s tenure with the Los Angeles Chargers continues its roller-coaster ride.

With the Chargers welcoming the Las Vegas Raiders this week, it’s remains to be seen if Jackson’s backside is once again attached to the bench.

It’s a costly seat for the Chargers, not so much for Jackson.

L.A. coughed up $82.5 million for Jackson, a former All-Pro from the New England Patriots, and to date, only an aggressive investment in bitcoin would be worse.

Jackson’s first year with the Chargers was a wash when he suffered a season-ending knee injury. This year has been nearly as rocky with a still-mending Jackson getting beat and committing bonehead mental miscues in the first two games.

The result was Jackson being a healthy scratch when the Chargers beat the Minnesota Vikings on Sunday.

It will be determined if Jackson is on sabbatical this Sunday as well. Yes, Jackson is bewildered by his situation.

“I can tell you I’m confused, I don’t know what’s going on,’’ Jackson told reporters. “But that’s not the real answer of why I didn’t play last week or why I didn’t start. That’s above me.’’

Jackson, obviously, isn’t referring to his strain on the Chargers’ salary cap. No one gives it a bigger jolt than Jackson, whose number accounts for 7.5 percent of the cap, according to spotrac.com

With his $12 million base salary and $5 million bonus, Jackson’s $17 million cap figure for this year is tops among the Bolts. He’s in the second year of a five-year deal which came with a $40 million guarantee.

For that kind of dough, L.A. isn’t getting much in a secondary which has been problematic since coach Brandon Staley came aboard.

What’s clear is Jackson isn’t on board, attitude-wise, with the Chargers. Rookie defensive coordinator Derrick Ansley said as much on Thursday.

Asked if Jackson’s demotion was about his technique, Ansley shot down that notion.

“Not a technique issue,’’ Ansley said. “Just coming out here every day and being consistent...just come out every day and practice. Practice and do your part, and everything else will work itself out moving forward.’’

For the Chargers to advance in a positive manner, a steady Jackson is essential. Playing solid defense hasn’t been the Chargers’ forte and that’s why they’re paying Jackson so much.

Jackson does have an interception, although him trying to run it out of the end zone took some shine off it.

It’s also unfair to expect Jackson to contribute so heavily as he still finds his feet after a torn patella tendon. That his coaches’ strategy of him lined up in single coverage against Tyreek Hill in the season-opening loss to the Dolphins baffling.

“I’m not 100 percent,’’ Jackson said. “I know that the doctors know that. I’m not 100 percent so I’m doing my best.’’

His best isn’t good enough for the Chargers — yet.

Staley wouldn’t tip his hand on if Jackson sees action on Sunday. Staley’s decision will come after this week’s practices.

“I’m doing my best,’’ Jackson said. “And I don’t know what they expect me to do.’’