It can be that you are using some older indd file (v. 14.xx / CC2019) as template/source file. If that is case and you are also using the QR-code from that template, then you should instead of that make a brand new QR-code with the desired data.
For me that worked well. Because I am working with CC2020 and sometimes I use older indd files which were made with CC2019, were everything goes fine after conversion, except the QR-code, which btw is visible in Indesign but in the exported pdf it does not exist.
It can be that you are using some older indd file (v. 14.xx / CC2019) as template/source file. If that is case and you are also using the QR-code from that template, then you should instead of that make a brand new QR-code with the desired data.
For me that worked well. Because I am working with CC2020 and sometimes I use older indd files which were made with CC2019, were everything goes fine after conversion, except the QR-code, which btw is visible in Indesign but in the exported pdf it does not exist.