I think it also depends of your SIM has active international pack or not...
As, many UPI apps check SIM info periodically... so they may stop working in between if they are not able to authenticate the SIM in your phone (I am not sure though)
Atleast for me, it happened in India where, as soon as my SIM stopped working (out of range for 3 days... *bsnl), UPI stopped working too (but it was I think 8-9 month back)