Whose responsibility for 1099?

Participant ina plan took a distribution in early 2023 from his account with Provider 1.  Never cashed the check.  In the interim, the plan transferred to provider 2.

Meanwhile, the check got stale dated and Provider 1 sent the proceeds to Provider 2 who put it in their Unclaimed assets account.  Subsequently, the funds got paid out to his IRA.

The participant is looking for a 1099-R. 

Neither company is claiming responsibility for the 1099-R. Provider said because the check went stale dated, they have no responsibility.  Provider 2 is saying they won’t doing it either since the distribution didn’t happen on their system.

Any idea whose responsibility this is?

It is ultimately the Plan Administrator's responsibility to send a 1099-R to any participant who received a distribution during the year. If the Plan Administrator's agreements with their service providers don't cover providing a 1099-R under a specific set of circumstances, then they should make other arrangements to have the 1099-R sent to the participant. For example, maybe their TPA or tax preparer could prepare the form, given the necessary information.

So recordkeeper 1 decided that since the check went stale, they wouldn't do the 1099-R? 

If the check had been written in December would they still be waiting for it to clear before deciding to issue the 1099 for last year?

I agree with CBZ that it is the Plan Administrator that ultimately has to make sure the 1099-R is sent to the participant, and that service agreements with the service providers should address who has that responsibility. 

The IRS has a process for situations where an individual does not receive the forms they need to file their personal tax return:  https://www.irs.gov/taxtopics/tc154

The IRS not only will get involved in, shall we say, motivating the payer they also will provide the individual with a Form 4852 so the individual can file their return.  (Given the information provided about the situation, I would suggest giving the IRS service provider 1's contact information.)

Relevant to Bri's comment, I understand that no matter when the 1099-R is sent, the participant is on the hook for reporting the distribution as having occurred in 2023.

The situation in the original post says the payment ultimately was made to an IRA so none of this should impact the individual's tax calculations.