Error when saving dashboard with mixed data sources and merge transformation (Grafana OSS 11.4.0)

Hi Grafana Community,
I’m encountering an error when trying to save a dashboard under specific conditions. I would appreciate any insights or guidance you can provide.

Grafana Version:
Grafana OSS 11.4.0 (Windows)
Installer: grafana-11.4.0.windows-amd64.msi

Error Message:
An unexpected error happened
Details: TypeError: Cannot read properties of null (reading ‘replace’)

Conditions that trigger the error:

Queries

DataSource: Mixed
A: Hinemos-datasource-1
B: Hinemos-datasource-2
Both data sources use the same plugin and have identical query structures.
Saving works when only A or B is used individually.

Transformation

Using “Merge series/tables” to combine the results.
The merged summary values display correctly before saving.
The error occurs when clicking the “Save dashboard” button.

If there is any known workaround or documentation related to this issue, I would be very grateful for your help.
Best regards,

It will be good idea to upgrade to the latest version in that version serie at least, so 11.4.8. You can read release notes/change logs to check if that bug was fixed.