Dear @Herzog

Could you please provide me with the code which is not working for you? I have tried to reproduce your desired behavior, and for me, everything is working fine.

Please take a look at the below code:

.html:

<div class="container">
  <div class="row">
    <div class="col-md-6 mx-auto my-5">
      <mdb-stepper #stepper [linear]="true">
        <mdb-step name="Step 1" [stepForm]="firstFormGroup">
          <form [formGroup]="firstFormGroup">
            <div class="md-form">
              <input type="text" class="form-control" mdbInput mdbValidate formControlName="email">
              <label for="">Email</label>
              <mdb-error *ngIf="email.invalid && (email.dirty || email.touched)">Input invalid</mdb-error>
              <mdb-success *ngIf="email.valid && (email.dirty || email.touched)">Input valid</mdb-success>
            </div>
          </form>
          <button mdbBtn size="sm" color="primary" (click)="stepper.next()">CONTINUE</button>
        </mdb-step>
        <mdb-step name="Step 2" [stepForm]="secondFormGroup" *ngIf="email.valid">
          <form [formGroup]="secondFormGroup">
            <div class="md-form">
              <input type="password" class="form-control" mdbInput mdbValidate formControlName="password">
              <label for="">Password</label>
              <mdb-error *ngIf="password.invalid && (password.dirty || password.touched)">Input invalid</mdb-error>
              <mdb-success *ngIf="password.valid && (password.dirty || password.touched)">Input valid</mdb-success>
            </div>
          </form>
          <button mdbBtn size="sm" color="primary" (click)="stepper.next()">CONTINUE</button>
          <button mdbBtn size="sm" color="secondary" (click)="stepper.previous()">BACK</button>
        </mdb-step>
        <mdb-step name="Step 3" label="Step 3 label" *ngIf="password.valid">
          <p class="pl-2">Finish!</p>
          <div class="step-actions">
            <button mdbBtn  size="sm" color="primary" (click)="onSubmit()">SUBMIT</button>
          </div>
        </mdb-step>
      </mdb-stepper>
    </div>
  </div>
</div>

.ts:

firstFormGroup: FormGroup;
  secondFormGroup: FormGroup;

  ngOnInit() {
    this.firstFormGroup = new FormGroup({
      email: new FormControl('', [Validators.required, Validators.email])
    });
    this.secondFormGroup = new FormGroup({
      password: new FormControl('', Validators.required)
    });
  }

  get email() { return this.firstFormGroup.get('email'); }
  get password() { return this.secondFormGroup.get('password'); }

  onSubmit() {
    // do something here
  }

Best Regards,

Damian