Can't seem to install pre-release helmrelease (A.B.C-alpha.N)

[joaocc]

Hi,
Trying to install the alpha version of a chart, using flux 2.2.3 with pre-release patch.

The following helm command runs well on cli.

helm upgrade --dry-run vcp vcluster-platform --install --repo https://charts.loft.sh/  --version 4.0.0-alpha.5 --namespace test-vcp

However, when I try to install via flux, with the following config snippets, I get an error:

---
apiVersion: source.toolkit.fluxcd.io/v1beta2
kind: HelmRepository
metadata:
  name: loft-sh.vcluster
  # name: vcluster
  namespace: flux-system
spec:
  interval: 25h
  url: https://charts.loft.sh
---
apiVersion: helm.toolkit.fluxcd.io/v2beta1
kind: HelmRelease
metadata:
  name: vcp
  namespace: test-vcp
spec:
  interval: 5m
  chart:
    spec:
      chart: vcluster-platform
      version: "4.0.0-alpha.5"
      sourceRef:
        kind: HelmRepository
        name: loft-sh.vcluster
        namespace: flux-system
      interval: 5h
...

Message
invalid chart reference: failed to get chart version for remote reference: no 'vcluster-platform' chart with version matching '4.0.0-alpha.5' found
Reason
InvalidChartReference

Besides the manual helm command running well, the manual inspection of index.yaml and downloading the tgz all seem to work.
Is there any flag that prevents the specification of pre-release releases?
Any ideas?
Thx