Letsencrypt txt record creates and automatically disappears

I assume you have been following the install directions from https://github.com/jetstack/cert-manager/tree/master/deploy/charts/cert-manager to get the latest cert-manager v0.11.0 instead of using the old version from the Che install doc which lists v0.8.1?

Please run this command and paste the output. Specifically we want to check the status of the ACMEv2 order.

kubectl describe Certificates -n che
kubectl describe ClusterIssuer -n che

Please see my in-line notes on the commands you ran.

[ec2-user@ip-172-31-90-16 microchip]$ kubectl get Certificates -n che   <=== correct invocation
NAME      READY   SECRET    AGE
che-tls   False   che-tls   1h

[ec2-user@ip-172-31-90-16 microchip]$ kubectl get Issuer che            <===== are you using cert-manager in the 'default' namespace? If not a namespace should be specified here.
Error from server (NotFound): issuers.certmanager.k8s.io "che" not found

[ec2-user@ip-172-31-90-16 microchip]$ kubectl get Issuer che-tls        <===== are you using cert-manager in the 'default' namespace? If not a namespace should be specified here.
Error from server (NotFound): issuers.certmanager.k8s.io "che-tls" not found