Earned value for LOE tasks

How should we calculate the Earned value for LOE (Level of Effort) tasks ?

Use usually apply 0-100 basis for such tasks. LOEs are duration driven activities and they can be statused based on period elapsed.

Level of Effort by definition do not accrue progress. For LoE, the EV always equals the PV (or BCWS in old money). The only question is at what point they start to accrue EV. Strictly speaking it will be according to the baseline, i.e. as soon as the baseline says we start accruing PV, then we would accrue EV at exactly same rate (and value). However the task may not yet have started, therefore a positive cost variance will occur. No schedule variance, ever.