Dagger of Venom and Constitution

I have a Rogue that has a Dagger of Venom. When the Dagger of Venom is "checked" in her inventory, her Constitution score goes to 152101 and a modifier of 76045. I uncheck the Dagger of Venom, and it goes back to 16 (what it should be). So far, we have been solving the problem by leaving it "unchecked", but then it is not "equipped". I've deleted the Dagger of Venom from the character sheet, and the problem goes away. I add the Dagger of Venom from the compendium, and it is fine...until Level Up, then it goes all wonky again. Is the Dagger of Venom from the compendium bugged? 

Hi Moosey Jo,  Which character sheet are you using? If you don't know please supply a screenshot of the sheet. 

Standard 5e character sheet

Unfortunately there is no character sheet by that name, could you please supply a screenshot so the sheet could be identified? There are many 5e sheets, and there are multiple game systems that are "5e" as well.

This is the character sheet in question:

I checked that on my end, the compendium item is not bugged, but what happens is the peice of equipment gets bugged.  PLEASE, do not fix this yet if you don't mind? I am notifying a Dev that has asked me to keep an eye out for this bug, it has been difficult to track down.  If you really need to fix it (such as a game soon), could you duplicate the character first?  The fix: delete the item, drag a copy from the compendium

Since this has happened a number of times, I have fixed it in the past exactly as you described, by deleting the item and dragging a new copy from the compendium. I have also discovered that if I just "unequip" the dagger, the Con goes back to normal. So we will just keep it unchecked. Thank you for your help on this.