That's interesting that you mention Lucidlink. In our office we have recently taken our email off-site (we used to host it ourselves) and were looking at moving all of our data to a cloud service too. When we initially looked at it, one IT company suggested cloud based storage with IBM and the use of Lucidlink to manage the data transfer as I believe it splits the files in to smaller packets and should speed up the transfer rates more a kin to being on a local network. I think this company were just trying to sell us a product. We have since stated a process of changing our off-site backup to a cloud based system but maintaining all of our data locally as we were strongly advised by the company we eventually engaged not to store CAD data in the cloud as the files are just too large to be dealt with properly. This also applied to video production and photography production files and software. We were told a cloud based storage system is fine for database systems and word, excel files etc. I suspect, as you say, it could be an issue with the Lucidlink connection. I know Archicad goes through a complex process when opening, saving and closing files.
ArchiCAD 4.5 - Archicad 26UKI Apple Silicon 5003
macOS Ventura (13.4)