[BUG] Dash 1.6 Datatable disables all callbacks if not in initial layout

[HansKallekleiv]

Describe your context

dash                 1.6.0  
dash-core-components 1.5.0  
dash-html-components 1.0.1  
dash-renderer        1.2.0  
dash-table           4.5.0  

Same issue as #998 .
If DataTable is used in the app but not included in the initial layout callbacks are not working.

Small example using dcc.Tabs below.
Here the first rendered tab has a dcc.Graph which is populated in a callback.
The second tab has a empty DashTable.
With dash > 1.5.1 it is necessary to first navigate to the tab with the DashTable before the callback on the first tab is working.

# -*- coding: utf-8 -*-
import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output
import dash_table

app = dash.Dash()

app.layout = html.Div(
    children=[
        dcc.Tabs(
            children=[
                dcc.Tab(
                    children=[
                        html.Button(id="btn", children="Update graph"),
                        dcc.Graph(id="example-graph"),
                    ]
                ),
                dcc.Tab(children=dash_table.DataTable(id="example-table")),
            ]
        ),
    ]
)

@app.callback(Output("example-graph", "figure"), [Input("btn", "n_clicks")])
def update_graph(clicks):
    return {
        "data": [{"x": [1, 2, 3], "y": [4, 1, 2], "type": "bar"},],
    }

if __name__ == "__main__":
    app.run_server(debug=True)

Describe the bug

If a dash_table.DataTable is included in the app, but not in the initial layout, app callbacks are not working. After the table has been added to the layout the callbacks works correctly.

Expected behavior
The callbacks should work.

[josephcappadona]

I'm also encountering this bug. Downgrading to dash==1.4.1 solved the issue for me, but I am awaiting a better workaround.