6:15 PST -- Sources close to Travis tell us the rapper signed the deal in good faith -- thinking if he held up his end of the contract, so would Lyor Cohen's LCAR -- however, that wasn't the case. We're told Travis felt he was managing his own career as Cohen and company weren't lifting a finger for him ... so he left for a better management company.

Our source says it's ridiculous that Cohen, the head of global music at YouTube, would file such a frivolous lawsuit.

Much like Kylie Jenner's ex, her new bf Travis Scott's got a problem paying his bills ... at least according to his ex-managers who claim he's a couple million in the hole with them.

Travis' old pals at LCAR Management say the rapper signed a 3-year contract in Oct. 2014 which guarantees them 15% of everything he makes in entertainment. In docs, obtained by TMZ, they say that should've earned them at least $2 million by now.

Their problem ... Travis has only paid about $37k, according to the suit. LCAR says it's made repeated efforts to get the dough since 2015, but all they got was a letter from Scott's attorneys saying their services were no longer needed.

LCAR says it has a signed deal which Travis needs to honor. It's suing to get an accounting of what he's earned, and to get paid in full. We've reached out Travis' current reps ... no word back yet.

This could trigger PTSD for Kylie.