We were just trying to buy two senior Swiss travel passes for 15 days, and were unable to complete the transaction. We plan to be in country on 26 August. Is there a limit to when we can buy passes? There was no explanation why we couldn't buy the passes.
From what site were you trying to buy this pass?
The 15-day Swiss Travel Pass for visitors does not come in a Senior version. There is a regular pass and a youth pass, but nothing for older adults.
https://www.sbb.ch/en/leisure-holidays/inspiration/international-guests/swiss-travel-pass.html
The 1-year Swiss Pass for Swiss citizens does have a senior version, It they say “ Senior Citizens” they literally mean “citizens”. Tourists cannot buy this pass, nor, given the price, would one want to.
https://www.sbb.ch/en/travelcards-and-tickets/railpasses/ga/senior-citizens.html