Cannot save Flux Dev checkpoint merged with LoRAs

I am trying to merge LoRAs into the [single-file Civitai checkpoint](https://civitai.com/models/618692/flux) of Flux Dev using the `Merge FLUX LoRA` util from the `origin/sd3-flux.1 branch`.

The merge proceeds with no error message in under 10 seconds. The terminal's last line states `saving to: /mypath//kohya_ss/models/mymodel.safetensors`.

However, no model actually gets exported.

This happens with:

- Single LoRA merged into Flux Dev
- Multiple LoRAs merged into Flux Dev
- Two LoRAs merged together with no checkpoint involved

Is this merging util actually functional or just preparatory work for a future release?

Start with the `Merge FLUX LoRA` utility on the `origin/sd3-flux.1` branch and reproduce the merge for a Flux Dev checkpoint, a single LoRA, and multiple LoRAs. Check why the reported `saving to: /mypath//kohya_ss/models/mymodel.safetensors` does not produce an exported model; done means each supported merge case writes the expected checkpoint or reports a clear failure.

Written by the indexing model from the issue text.