Nothing contentious comes to mind. Banks are probably the biggest reason that trades might need assistance. For example:

• Bank rejects payment to the payee
• Bank rejects payment to the payer
• Bank holds payment from the payee for extra checks and either credits it or returns it

I use bank to refer to any financial services provider; eg Zelle, Strike etc.

Similar to Bisq 1, Bisq 2 provides mediation support should traders need assistance.