Well, maybe is because I am newbie to Ionice. In fact, the problem with modal pages is still present, I just discovered. If I declare the modal page in declarations/entryComponents at app,module.ts, I get the error I mentioned. I moved to the parent page (the one that actually calls the modal) and the compiler error dissapeared…but now it pops out again when I try to call the modal, so, at this moment, I don’t know how to properly call a modal page with lazy loading 
modal page declaration (muestra.module.ts):
import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule } from '@angular/forms';
import { Routes, RouterModule } from '@angular/router';
import { IonicModule } from '@ionic/angular';
import { MuestraPage } from './muestra.page';
const routes: Routes = [
{
path: '',
component: MuestraPage
}
];
@NgModule({
imports: [
CommonModule,
FormsModule,
IonicModule,
RouterModule.forChild(routes)
],
declarations: [MuestraPage],
entryComponents: [MuestraPage]
})
export class MuestraPageModule {}
parent page declaration (muestras.module.ts):
import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule } from '@angular/forms';
import { Routes, RouterModule } from '@angular/router';
import { IonicModule } from '@ionic/angular';
import { MuestrasPage } from './muestras.page';
import { ComponentsModule } from '../../components/components.module';
const routes: Routes = [
{
path: '',
component: MuestrasPage
}
];
@NgModule({
imports: [
CommonModule,
FormsModule,
IonicModule,
ComponentsModule,
RouterModule.forChild(routes)
],
declarations: [
MuestrasPage
],
entryComponents: [
],
schemas: [
]
})
export class MuestrasPageModule {}
caller method:
async nuevaMuestra() {
const modal = await this.modalController.create({
component: MuestraPage,
componentProps: {
tipo: this.currentTab.toUpperCase(),
statusTunel: this.tunel.status,
muestras: this.muestras.filter(x => x.tipo == this.currentTab.toUpperCase())
},
backdropDismiss: false
});
modal.onDidDismiss()
.then(res => {
if (res.data)
this.agregarMuestra(res.data);
});
return await modal.present();
} // nuevaMuestra
The error I have right now:
ERROR Error: Uncaught (in promise): Error: No component factory found for MuestraPage. Did you add it to @NgModule.entryComponents?
When I declare MuestraPage in MuestrasPage module, then I get this when try to load the modal:
ERROR Error: Uncaught (in promise): Error: Type MuestraPage is part of the declarations
of 2 modules: MuestraPageModule and MuestrasPageModule! Please consider moving
MuestraPage to a higher module that imports MuestraPageModule and
MuestrasPageModule. You can also create a new NgModule that exports and includes
MuestraPage then import that NgModule in MuestraPageModule and
MuestrasPageModule.