Blocks will show in the Student's Enrollment but not when Managing the Enrollment if the Blocks are Inactive. To check this please take the following steps. 
  1. Go to Core > School > Blocks
  2. Select the proper School Level and locate the missing Block
  3. If the Block is marked "Inactive" set it to "Active"
  4. The Block will then appear in when you click the Manage Button in the Student's Enrollment Record