Upload capabilities not working anymore for Box project having multi company members

Hello
We create project share between My company box corporate account , our business Partner and the Final Customer.  all looks to work fine since 6 month , but now we face from "final Customer" unability to upload document. 
Have  check the role nothing have change , and have also ask people to clear theirs browser cache and retry sound it is the same issue. Users having IBM mail box still able to upload looks to impact only  people having ca-gip.fr mail box