SPIERSview doesn't close when loading data

[RussellGarwood]

Describe the bug
When loading data, if you click close in SPIERSview a dialogue appears saying are you sure you want to close. If you say yes, the window still does not close (in Linux - not tested on windows)

To Reproduce

1. Start loading a model
2. Cick close on the window
3. Click OK in dialogue
4. Window does not close

Expected behavior
Window should close

Screenshots
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Desktop (please complete the following information):
Linux, master branch, new build

Additional context
Add any other context about the problem here.

[alanspencer]

Same on Windows and macOS too. On Windows the application does close, but only once the model has finished loading.