In Tracker's reports, the formulas which can be activated don't work when one formula is activated on a "Computed" field.
In the screenshot "Tuleap Report issue with Computed values - OK.png", a formula is activated on the "Etat" column, and works well.
In the screenshot "Tuleap Report issue with Computed values - NOK.png", another formula is activated on the "Initial Effort Computed" column: but this doesn't work. Moreover, it also deactivates the formula on the "Etat" column.
I also had this issue on the MyTuleap test server I had a few month ago, and just realized this is also present on my community Edition on premise.