Spinning wheel of death with EVERY command

On a particular project, no matter what command I seem to carry out I see met with the spinning wheel of death. This can be a simple length change of a region or an 'undo' but it's every time and it's only on one project. This is not a particularly large project, and I am running from a fully updated top notch iMac. I feel that this occurred since I carried out a 'split at all transients command' but surely there is a way around this.

I have tried to 'Delete Redundant Automation Points' as suggested here

https://www.logicprohelp.com/forum/viewtopic.php?t=112266

but no joy.

Can anyone help me with this?