Bouncy Castle c#, how to generate pfx file with full certification path - ssl

Question

I have an issue with generation pfx file with full certificate chain which is correctly read as X509Certificate2 object in .net core for authentication. I tried various approaches but with no luck.
I have a chain generated by OpenSSL and I use last certificate and private key to generate user certificates for authentication.
Finally, I have PEM files with certs (each cert from a chain in a separate file)
-----BEGIN CERTIFICATE-----
MIIFR[....]Aerk=
-----END CERTIFICATE-----
etc.
In webapi controller I have
X509Certificate2 clientCertificate =
this.Request.HttpContext.Connection.ClientCertificate;
X509Chain x509Chain = new X509Chain(){ ChainPolicy = new
X509ChainPolicy({...}};
x509Chain.Build(clientCertificate))
var elements = x509Chain.ChainElements.Cast<X509ChainElement>()
// in elements variable I expect to have more than one item but I don't have
How can I generate pfx in Bouncy Castle in the correct way to achieve it?
Below some code snippet for pfx file creation which generates pfx but is read as X509Certificate2 with only one chain element. How to modify it to have all of them available?
Pkcs12Store store = new Pkcs12Store();
X509CertificateEntry[] chain = new X509CertificateEntry[5];
X509Certificate cert1 = certParser.ReadCertificate(new
MemoryStream(Encoding.UTF8.GetBytes(certString1)));
X509CertificateEntry certificateEntry1 = new X509CertificateEntry(cert1);
chain[0] = certificateEntry1;
// I adds all certs in order from user cert to root one (self signed)
store.SetKeyEntry(csr.GetCertificationRequestInfo().Subject.ToString(), new
AsymmetricKeyEntry(key.Private), chain);
using (var filestream = new FileStream("./full.cert.pfx"), FileMode.Create,
FileAccess.ReadWrite)){
store.Save(filestream, "".ToCharArray(), new SecureRandom());
}