On Activity Types (CR.10.20.00), you can specify if a certain type of Activity should track time and costs. If time is not being tracked, the Billable box will go away as well.

​@temberson Somewhere along the way ours changed again and the Track Time and Costs is automatically checked, however it won’t allow the email to be sent unless billable time is entered, or the Billable checkbox is unchecked. We’ve been working around it by unchecking the billable checkbox before sending the email. We learned the hard way that if the Track Time and Costs box is unchecked it takes away the Project field, so the activity is no longer linked to the project it was created in. Here is another post that I detailed out our issues in depth. At the time of the post there was a possibility of it changing in the 24R1 release. We have not upgraded yet, so I’m not sure if anything concrete transpired or not.  

Why can't activities be created in Projects without the Track Time and Costs box checked? | Community

We only have one active billing rule that we utilize for association with the tasks on the project and that rule is set to Progress Billing.

Unfortunately, none of the options solve the issue.

I have included a sample of when I was adding a task to “Assign estimator”.  You can see that the activity type does not have the tract time and costs box checked, but when I create the activity within a project, it still has the track time and costs checked.

Is your project’s billing rule set to a Time And Material type? I suspect, but cannot say for sure, that this would be the cause, as I assume the system is expecting you to be entering billable time.

Hi @BDreith were you able to find a solution? Thank you!

We just ran into a similar problem. We are in the implementation phase and when we tested emailing activities a couple weeks ago everything worked fine. Now, all of a sudden, we get the following error: 

If I click on the details tab, the Track Time and Costs box is not checked. If I check it and then uncheck it, it’s fine and I’m able to send the email without having to enter additional information. I’ve looked everywhere I can think of to see if there was a setting that might have been changed. Under activity types the box isn’t checked, we don’t have approvals required on the project or task level. I don’t know where else to look to fix this, or what setting could have been changed for this to start happening.

Hi ​@mnecaise, Did you resolve this issue? We are running into this roadblock as well. I have tried defaulting that Billable checkbox to false in a customization project but still no luck.