Mystery of the glitchy Excel Timeline Template

Perhaps you can help me solve this issue. I created a timeline using Excel template called "Timelines with milestones (yellow)" please view below

Screen Shot 2019-08-09 at 10.42.28.png

Everything went smoothly, bounds were adjusted, data was entered and it worked intuitively. I even gave a presentation to my boss and showed him that I could adjust the timeline by simply changing a date or position.

Several days later I decide to use the same template to create a new chart. That's where the problems begin. First, I changed the bounds THEN when I followed by changing the dates, everything was all messed up. All the data shifted down the axis every time I changed a date. It was working fine a week ago, and now it's all haywire.

I even went back to the original document where I had just done a presentation a week earlier and it had worked. It was doing the same on that one as well! I restarted the computer, but same issue. What the heck? Why is this suddenly happening? Now I can't even use the template at all. It seems that it's somehow connected to changing of the bounds, is my guess. Halp =/

glitchy timeline.xlsx

File has been attached.

In terms of edits, I simply suggest you take any date and change the month, at least by 2 months, and see if everything shifts down the timeline. I am finding that by changing one date, it affects all the other dates. This is strange because only a week ago I used this template to make a complete timeline with new data and nothing shifted like that at the time.

That is, in fact, the solution I was aiming for. I had originally created the Excel chart with all of the dates in order. However, when I decided to add new dates that is where the problem occurred. I tried your method and for the moment, seems to be a good solution. I am hesitant to say it's resolved until I can really utilize this new feature by adding and moving around dating a bit more, but your advice is much appreciated! Thank you!!