gpg keys failure prevent yum install of Intel libraries

To install intel-daal-core-2018.1-163 on CentOS, I used these two repo files:

/etc/yum.repos.d/intel-mkl.repo:

[intel-mkl-core-2018.1-163] 
name='Intel(R) Intel Math Kernel Library' 
baseurl=https://yum.repos.intel.com/mkl 
enabled=1 
gpgcheck=1 
repo_gpgcheck=1 
gpgkey=https://yum.repos.intel.com/mkl/setup/PUBLIC_KEY.PUB 
debuglevel=10 
enabled=1

/etc/yum.repos.d/intel-daal.repo:

[intel-daal-core-2018.1-163] 
name='Intel(R) Data Analytics Acceleration Library' baseurl=https://yum.repos.intel.com/daal 
enabled=1 
gpgcheck=1 
repo_gpgcheck=1 
gpgkey=https://yum.repos.intel.com/daal/setup/PUBLIC_KEY.PUB 
debuglevel=10 
enabled=1

But, from this morning, the yum install command (sudo yum install intel-daal-core-2018.1-163) fails with:

failure: repodata/repomd.xml from intel-mkl-core-2018.1-163: [Errno 256] No more mirrors to try. https://yum.repos.intel.com/mkl/repodata/repomd.xml: [Errno -1] Gpg Keys not imported, cannot verify repomd.xml for repo intel-mkl-core-2018.1-163

However, if I stop checking the gpg keys, namely - I change the repo files to:

[intel-mkl-core-2018.1-163] 
name='Intel(R) Intel Math Kernel Library' 
baseurl=https://yum.repos.intel.com/mkl 
enabled=1 
gpgcheck=1 
repo_gpgcheck=0 
#gpgkey=https://yum.repos.intel.com/mkl/setup/PUBLIC_KEY.PUB 
debuglevel=10 
enabled=1 


[intel-daal-core-2018.1-163] 
name='Intel(R) Data Analytics Acceleration Library' 
baseurl=https://yum.repos.intel.com/daal 
enabled=1 
gpgcheck=0 
repo_gpgcheck=0 
#gpgkey=https://yum.repos.intel.com/daal/setup/PUBLIC_KEY.PUB 
debuglevel=10 
enabled=1

And do:

sudo yum clean all ; sudo rm -rf /var/cache/yum

Then sudo yum install intel-daal-core-2018.1-163 is successful.

Googling didn't find any notice from Intel that they changed something.
Does anyone know what's the reason for the yum failure of gpg keys?