I currently have the same issue at my office. I've communicated with Graphisoft (US) and they shared with me this is not an isolated issue and are working on a resolution. Perhaps to be included in the next hotfix
As for why it is happening, I do not know. This ArchiCADwiki article
states one possibility which is the log files of the project are too large. There is a solution included in the article, although it did not resolve the issue taking place at my office.
Unfortunately the biggest conflict this bug presents is my inability to rollback the backup of TW projects should it crash or malfunction. As a work-around in the meantime, I have asked our project teams to manually save their TW files as a .pln project for backup. If anyone has a better suggestion, I'm all ears.
For me, the BIM Server Manager 14 will still run as long as I don't attempt to access any of the project settings. Here's to a speedy release of the next hotfix!