Transition not working on text-fill-color

Transition not working on text-fill-color and I cannot figure out the issue here.

.project {
  -webkit-text-fill-color: #000;
  -webkit-background-clip: text;
  -webkit-text-stroke: 1px #000;
  transition: all ease-in 3s;
}

.project:hover {
  -webkit-text-fill-color: transparent;
}
<div class="project-container">
  <div class="project">
    Transition Not Working
  </div>
  <div>

From the MDN documentation:

Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

I replaced -webkit-text-fill-color with color, and it seems to work just fine

.project {
  color: #000;
  font-size: 48px;
  -webkit-background-clip: text;
  -webkit-text-stroke: 1px #000;
  transition: all ease-in 0.3s;
}

.project:hover {
  color: transparent;
}
<div class="project-container">
  <div class="project">
    Transition Not Working
  </div>
<div>