BIND9 SERVFAIL using dig on UBUNTU server 18

I am setting up a nextcloud+onlyoffice server on ubuntu server 18 and a LAN DNS for my office to go with it. I’m not a real IT guy but I follow tutorials and read forums. Also, being in China I don’t have google and most my searches find irrelevant answers… I still saw many people had an error similar to mine but no solution worked for me. I’m sure it’s a stupid obvious mistake but since I’m not familiar with the BIND9 syntax, I just don’t see it… Here is my named.conf.local :

    zone "plateforme.local" IN {     type master;     file "/etc/bind/zones/db.plateforme.local";     //allow-transfer{211.66.139.29;};     allow-update { none; };     allow-query { any; }; };  zone "139.66.211.in-addr-arpa" IN {     type master;     file "/etc/bind/zones/db.rev.plateforme.local";     allow-update {none;}; }; 

my db.plateforme.local :

; ; BIND data file for local loopback interface ; $  TTL    604800 @   IN  SOA ns.plateforme.local. root.plateforme.local. (                   33    ; Serial              604800     ; Refresh               86400     ; Retry             2419200     ; Expire              604800 )   ; Negative Cache TTL ;  ; name servers - NS info         NS  ns.plateforme.local.  ; name servers - adress ns  IN  A   211.66.139.29  ; name servers - A records nextcloud   IN  A   211.66.139.29 onlyoffice  IN  A   211.66.139.29 

Here is db.rev.plateforme.local :

; ; BIND reverse data file for local loopback interface ; $  TTL    604800 @   IN  SOA ns.plateforme.local. root.plateforme.local. (                   17    ; Serial              604800     ; Refresh               86400     ; Retry             2419200     ; Expire              604800 )   ; Negative Cache TTL ;  ; name servers - NS info     IN  NS  ns.plateforme.local.     IN  NS  localhost.  ; name servers - adress 29  IN  NS  ns.plateforme.local.  29  IN  PTR nextcloud.plateforme. 29  IN  PTR onlyoffice.plateforme.local. 

Here is the result of dig nextcloud.plateforme.local :

nextcloud@nextcloud-server:/etc/bind/zones$   dig nextcloud.plateforme.local. ; <<>> DiG 9.11.4-3ubuntu5.1-Ubuntu <<>> nextcloud.plateforme.local. ;; global options: +cmd ;; Got answer: ;; WARNING: .local is reserved for Multicast DNS ;; You are currently testing what happens when an mDNS query is leaked to DNS ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 42787 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1  ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 65494 ;; QUESTION SECTION: ;nextcloud.plateforme.local.    IN  A  ;; Query time: 0 msec ;; SERVER: 127.0.0.53#53(127.0.0.53) ;; WHEN: mar. mars 12 10:25:52 HKT 2019 ;; MSG SIZE  rcvd: 55 

and the reverse dig dig -x 211.66.139.29 that surprisingly works :

nextcloud@nextcloud-server:/etc/bind/zones$   dig -x 211.66.139.29  ; <<>> DiG 9.11.4-3ubuntu5.1-Ubuntu <<>> -x 211.66.139.29 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63404 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1  ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 65494 ;; QUESTION SECTION: ;29.139.66.211.in-addr.arpa.    IN  PTR  ;; ANSWER SECTION: 29.139.66.211.in-addr.arpa. 0   IN  PTR nextcloud-server. 29.139.66.211.in-addr.arpa. 0   IN  PTR nextcloud-server.local.  ;; Query time: 120 msec ;; SERVER: 127.0.0.53#53(127.0.0.53) ;; WHEN: mar. mars 12 10:39:53 HKT 2019 ;; MSG SIZE  rcvd: 121 

I’d be very thankful if someone could help… I’m setting up this server for our team of 16 teachers because I had some computer science training over a decade ago, because we have need for such server and the offer in mainland China is limited and abroad out of reach… but I do it in addition to my duties as a teacher and it is draining my free time. I would greatly appreciate the help and advice of experts. Thank you in advance for your time !